Kremowka - Polish Custard Slice
Updated: Apr 13
Delicious vanilla custard cream sandwiched between layers of flakey and buttery pastry.
The cream is spiked with brown butter, vanilla and rum. The pastry is flakey and crisp on the outside with layers of buttery goodness in-between. Spelt, brown butter, vanilla and rum are bringing this bake onto the next level.
Many countries have their version of custard slice. No wonder! This type of treat is hard to resist. In today’s post we are sharing our take on Kremówka (pronounced kreh-moov-kah) - Polish Custard Slice.
For a good bake:
Pastry - the choice is yours - depending on how much effort you want to put into preparing this dessert. There are few options:
a) If you want a quick fix - go for store-bought, buttery puff pastry. You will need 2 sheets butter-based puff pastry (about 500 grams).
b) Rough puff with addition of spelt - included in the recipe and looks like on the pictures in this post. This is a quicker way of preparing flakey pastry. Layers are created by incorporating larger chunks of butter into flour and then by folding the pastry. For best results - make sure to chill ingredients (flour, butter, water mixed with vinegar, mixing bowl) before starting to prepare the pastry. When adding butter - coat each piece in flour and incorporate into flour by pressing in-between your fingers. For rough puff you want the pieces to resemble flat discs, the size of a medium-sized walnut. Once you achieve that - re-coat butter with flour again. By doing this you will make sure the butter will stay intact after water incorporation and during gentle kneading. There is a small amount of vinegar in this recipe - it will make your pastry slightly softer and easier to work with. Mix vinegar with water and chill before adding to flour/butter. You will make a small well in the centre of flour - add water and rather than knead - toss flour to hydrate the mixture and then mix for literally 30 seconds to a minute. Try to be brief, not to melt the butter. You may need to add 1-2 Tbsps ice-cold water to the mixture - but try not to go overboard. The temptation will be to add more water than is needed. Try to resist - the dough should be concise but not too wet. Chill the dough well between the folds. Before rolling, leave pastry for 5-10 minutes at room temperature - it will relax gluten and the dough will be easier to roll out (also less chance of butter starting to break up). Don’t be afraid of dusting the work surface and the top of the dough - just before folding make sure to brush off the excess flour. After folding, the dough can be stored in the fridge for up to 2 days.
c) All-butter wholemeal spelt pastry - this dough has less butter and higher hydration. It also has more wholemeal spelt (nutty, delicious flavour). It can be used in this bake too - make sure to roll it out 1cm thick and complete all the folds. In terms of texture - it will be more delicate than rough puff but in the same time it will be flakey, deliciously nutty and crisp.
d) Laminated pastry - if you are searching for a baking project - go for laminated dough. I don’t have on the blog the process for this pastry. I don’t do it that often. However, anytime I bake laminated pastry I use Joe Pastry blog or The Weekend Bakery .
Spelt - we love to bake with spelt. It gives gentle nutty notes to your pastry adding a new flavour dimension to the bake. What type of spelt flour to use? We use wholemeal spelt flour in our pastry bakes (texture is similar to organic Doves wholemeal spelt flour). You can use white spelt here but coarse flour will add more flavour and texture. If you are using Polish spelt - use type 630/650 or 1000. I’m leaving some scope for water adjustment in the recipe - wholemeal spelt will require additional 1-2 Tbsps water (as marked in the recipe).
Timing - if you are going for homemade pastry - both versions, as well as laminated pastry, can be stored in the fridge, after folds are completed, for up to 2 days (double wrap in cling film). I usually prepare pastry a day before and bake sheets when preparing custard.
Custard - blend or whisk cornflour/egg yolks/small amount of milk until smooth. Bring milk/sugar/cream mixture to simmer (just below boiling point) and in steady, thin stream start adding blended egg yolks. Cook on low heat, whisking constantly (otherwise you may end up with scrambled eggs). Once the whole mixture is added - continue to cook on low-medium heat for 2-3 minutes, whisking every so often. You want to achieve budino-like consistency. The mixture should be fairly thick - when you turn the spoon upside down it should hold for split second before dropping. It should be smooth. By cooking the mixture for 2-3 minutes you will also cook-out cornflour flavour. This custard then is spiked with warm brown butter, vanilla and rum - mix together briefly until combined. For the slice to set beautifully and achieve lovely texture you will beat the custard with butter. First though - the custard needs to cool down fully. Cover the mixture with cling film - place the film direct on the custard, so that it sticks to the surface - this way you will prevent the thick coating from forming (and lumpy texture as a result). When the custard is cooled you will beat unsalted butter until creamy and then add the custard until smooth mixture is formed. It will look fairly loose but the cream will set once the slice is refrigerated. Thanks to this technique the slice holds perfect shape when served - it tastes fantastic too!
Brown butter will add lovely flavour to vanilla and rum. All these notes are going to be subtle - nothing over-powering but together will form beautiful cream. Go for light brown, golden colour with small brown speckles (i.e. don’t brown the butter too much).
Vanilla - we use 3 types of vanilla in this slice - vanilla bean paste, vanilla pod and sugar. You can skip vanilla sugar and replace with regular sugar. If you don’t want to use vanilla pod - increase the amount of vanilla bean paste. All is included in the recipe below.
Tin - the portion below fits into 20x20cm square tin. If you want to use 22x33xcm tin - go with 1.5 portion.
Assembling here is easy. Layer of cream is sandwiched between two layers of pastry. Cutting may not be that easy though. How to prevent the pastry from breaking? I cut the top cover into small portions and place on top of the cream before chilling. This way you will need to cut only the bottom layer - it’s way less messy. Use bread knife.
Chilling - chill Kremówka for at least 4 hours, and preferably overnight. The cream will set beautifully. Leave at room temperature for 10-15 minutes and sprinkle with confectioners’ sugar just before serving.
Storage - store refrigerated for up to 3 days, loosely covered.
Kremowka - Polish Custard Slice Recipe
Yield: 9 slices (OR 12-15 slices if prepared in 22x33cm tin)
Time: 4hrs for pastry (mainly folding and baking) + 45min for custard prep and assemble + min 4hrs chilling
Tin: 20cmx20cm OR 22x33cm (prepare from 1.5 portion); at least 5cm deep
For the pastry (few options):
Shop-bought puff pastry (2 sheets of buttery puff pastry; about 500 grams)
Homemade laminated French pastry (see notes above)
OR the pastry on the picture (rough puff with spelt). You will need:
360g all-purpose (plain) flour
40g wholemeal spelt flour
1/2 tsp fine salt
330g unsalted butter, cut into 1cm cubes and cold
150ml ice-cold water + 1-2 Tbsps (15-30ml) if needed
10ml apple cider vinegar
For the custard:
60g unsalted butter, browned
1 vanilla pod
2 Tbsps (30ml) golden rum
450ml full-fat milk (split, 375ml+75ml)
150g sugar (I use 130g white sugar and 20g vanilla sugar)
200ml cream, 36 or 38% fat
1 tsp vanilla bean paste (or 2 tsps if not using vanilla pod)
6 egg yolks from large eggs (120g)
100g unsalted butter, room temperature
+30-50g icing/confectioner’s sugar to decorate
1. Prepare pastry (here ‘how to’ for rough puff with spelt):
a) Refrigerate ingredients: Before starting with pastry prepare all your ingredients and refrigerate for 1 hour before mixing. Place flours and fine salt in your main mixing bowl and whisk. Refrigerate (together with the bowl). Cut butter into 1cm cubes and refrigerate. Mix water (150ml) with apple cider vinegar and also refrigerate (use ice-cold).
b) Prepare the dough: When ready, start adding butter cubes into flour, coating each piece in flour mixture. Incorporate butter into flour by pressing the pieces between your fingers, flattening them into discs (the size of a medium walnut). Re-coat flat pieces in flour. Try to be swift at it, not to melt the butter. If the mixture is getting too warm - place back in the fridge for few minutes. When ready, make a well in the middle and pour 150ml ice-cold water mixed with vinegar, gently toss the flour around so that the two begin to form coarse mixture. After few seconds of gentle tossing, start gentle kneading (be brief; 30 seconds - 1 minute). If needs be - add 1-2 Tbsps ice-cold water. The dough shouldn’t be too wet - bring the dough together and divide into 2. Flatten each piece into disc (2-3cm thick), double wrap in cling film and refrigerate for 45 minutes.
c) Fold to create layers: Take out the dough and let rest at room temperature for 5 minutes before rolling. Lightly dust work surface with flour. Roll out the dough, 1 cm thick. You may opt to use some extra flour for dusting if the bottom and top layers are becoming sticky. When done, brush off any excess flour and fold the dough in half and then fold in half again into quarters. Do the same with the second disc. Double wrap the dough in cling film and refrigerate for 45 minutes. Repeat folding 3 times, remember to chill the dough in-between and give the dough 5 minutes rest at room temperature before rolling out. When all the folds are completed, depending on your time - you can opt to leave wrapped pastry in the fridge for up to 2 days or continue with shaping and baking.
d) Shape&Bake: Lightly dust your work surface, leave pastry for 5-10min at room temperature and gently roll out each disc into 20cmx20cm square (or 22x33cm if baking using 1.5 portion), 1cm thick (don’t roll out too thin). Trim edges to fit the tin. Refrigerate sheets for 30-45 minutes before baking. In the meantime, preheat the oven to 200C (180C fan forced). Bake each sheet for 45-50 minutes.
2. Prepare custard: Brown 60g of unsalted butter (go for light golden colour with gentle, small speckles), cut vanilla pod in half (length-wise), remove seeds and add to hot butter, place the remaining pod in the butter as well. Mix briefly. When the mixture is still warm but not hot, add rum, mix, cover and let it cool until ready to use. In a pot with heavy bottom mix milk (375ml) and sugar, bring to boil mixing every so often. Reduce the heat to low-medium, add cream and vanilla bean paste and whisk every so often. In a meantime, place remaining milk (75ml), egg yolks and cornflour in the blender and mix until smooth and combined. Go back to the milk/cream and when the mixture is hot, simmering (just below boiling point), start pouring in a steady, thin stream the egg/cornflour mixture, whisking energetically. Take your time and do it slowly, over low heat (otherwise you may end up with scrambled eggs). Once the mixture is combined, continue cooking on low-medium heat, whisking every so often for about 2 minutes. You want the mixture to thicken into budino-like consistency. This should take about 2-3 minutes. When you take small portion on the spoon and turn it upside down the mass should stay for a split second on the spoon before dropping back to the pot. You know then that this part is done. The mixture should be smooth. If it’s not - the temperature was too high or you cooked it for too long. Take the mixture off the heat, add lukewarm vanilla/rum brown butter (remove the pod beforehand, give it a proper squeeze). Whisk energetically until combined. Cover the mixture with cling film (place the film directly on top of the custard) and cool down fully (this will take some 30min to 1 hr). When ready, place butter (100g) in your main mixing bowl (make sure it’s at room temperature, but not oily), beat for 1 minute until smooth, then add 1/3rd of fully cooled custard and mix until combined, when smooth - add the rest of the custard and mix briefly until smooth.
3. Assemble: Place first sheet of baked and cooled pastry in the baking tin, layer with custard cream. Cut second sheet of pastry into portions and place on top of the custard. You may also opt to cover the custard with the full second sheet (cutting will be a bit more tricky then).
4. Chill: Loosely cover the tin and refrigerate your custard slices for at least 4 hours and preferably overnight. Leave the tin at room temperature for 10-15 minutes before serving. Use bread knife to cut into portions. Sprinkle with confectioners’ sugar just before serving.