Prekmurska gibanica — Slovenian cake with poppy seeds, curd cheese, walnuts and apples

Rub the base flour, 25 g sugar and salt with the 75 g cold butter into fine crumbs. Add the 50 g egg and quickly bring together without prolonged kneading. Flatten, wrap and chill for 30 minutes. Do not add water or flour. All the dough goes on the bottom, without trimming edges and without dusting while rolling.

Heat the 150 g milk almost to a boil. Pour over the dry ground poppy seeds, mix, cover and leave for about 20 minutes to absorb the liquid. Do not drain. Add the 60 g sugar and 4 g vanilla sugar, mix and cool. Divide all the thick filling into two equal parts. The poppy seeds receive more moisture from the sour cream mixture during assembly; do not use ready-made sweetened filling with dried fruit and nuts.

Mash the curd cheese with a fork or press through a ricer. Mix with the 50 g egg, 60 g sugar, 8 g vanilla sugar and 1 g salt. This should be a thick finely grainy filling, not runny cream cheese. The 800 g curd cheese has already been weighed without loose whey: do not drain anything now. Divide all into two equal portions and refrigerate until assembly.

Combine all 200 g finely ground walnuts with 60 g sugar and 4 g vanilla sugar. Divide into two equal portions. At this stage the filling is loose and dry; do not add milk or oil. Each layer receives a measured share of sour cream mixture and butter to keep it moist after baking.

Whisk the 500 g sour cream with 100 g eggs to make 600 g mixture. Allocate 100 g to each of the four poppy seed or walnut layers, 25 g to each of the four curd cheese or apple layers, and reserve 100 g for the top. Melt all 120 g butter without clarifying. Allocate 5 g to the first sheet, 20 g to each poppy seed and walnut layer, 5 g to each curd cheese and apple layer, then 5 g and 10 g to the two top sheets. Keep the sour cream mixture chilled.

Keep the washed apples unpeeled, remove stems and cores, then weigh 900 g edible parts. Coarsely grate and mix with the 70 g sugar and cinnamon. Divide into two equal portions with all the juice released. Do not squeeze, do not drain and do not stew the apples. Stir again just before adding, so both layers receive flesh and juice.

Preheat the oven to 175°C, conventional heat. Line the bottom and sides of a metal pan with inside dimensions of 30 × 30 cm and at least 7 cm tall with parchment. Do not grease with extra fat and do not dust with flour. Position the rack slightly below the center. This is a large layered cake; a shallower pan will not hold all the fillings and sour cream mixture.

Roll all the chilled dough between two parchment sheets into a 30 × 30 cm square about 3 mm thick. Transfer to the pan bottom, remove the upper parchment and press out uneven spots; press any scraps into the base. Do not make a high rim. Prick with a fork and prebake at 175°C for 12–15 minutes, until set on the surface but not deeply browned. Set aside for about 10 minutes. Leave the oven on.

Trim the 10 filo sheets to 30 × 30 cm squares. Divide all the narrow offcuts into eight small portions, one for each filling layer. This uses all 250 g pastry. Number the main sheets from 1 to 10 and keep under plastic wrap or a slightly damp cloth so they do not dry out; do not wet them. Have fillings, sour cream mixture, butter and spatula within reach.

Put filo sheet no. 1 on the prebaked base and brush with 5 g butter. Spread the first half of the poppy seed filling. Add one portion of filo trimmings over it, pour over 100 g sour cream mixture and drizzle with 20 g butter. Cover with sheet no. 2. Spread filling gently across the whole surface, including the corners, without pressing hard or tearing the thin pastry.

Spread the first half of the curd cheese filling on sheet no. 2. Add the second portion of trimmings, 25 g sour cream mixture and 5 g butter. Cover with sheet no. 3. Do not mix the curd cheese with the poppy seeds below: they should remain two separate layers. Spread filling in small portions so the thin pastry does not move with the spatula.

Scatter the first half of walnuts and sugars over sheet no. 3. Add the third portion of trimmings, pour over 100 g sour cream mixture evenly and drizzle with 20 g butter. Cover with sheet no. 4. Do not leave a dry mound in the middle; the mixture should moisten walnuts at the sides too. Do not add extra cream or milk.

Spread the first half of the apples with their share of juice over sheet no. 4. Add the fourth portion of trimmings, 25 g sour cream mixture and 5 g butter. Cover with sheet no. 5. The first set, from the bottom up, is therefore poppy seeds, curd cheese, walnuts, apples. Do not change the filling order and do not set aside bowl juices to discard.

Put the second poppy seed filling on sheet no. 5, then sheet no. 6 and the second curd cheese filling, sheet no. 7 and the second walnut filling, sheet no. 8 and the second apple filling. With each, add the next portion of trimmings and the same sour cream mixture and butter allocation as before: poppy seeds 100 g and 20 g, curd cheese 25 g and 5 g, walnuts 100 g and 20 g, apples 25 g and 5 g. Use all fillings and all eight portions of trimmings. There are eight filling layers in the end, with apples last.

Put sheet no. 9 over the final apples and brush with 5 g butter. Cover with sheet no. 10. Score only the two top sheets in a 4 × 6 grid for the eventual servings, without cutting into the fillings. Brush with the last 10 g butter and spread over the remaining 100 g sour cream mixture. Scrape the dishes; all butter and mixture are used. Pierce through the layers with a thin skewer to let steam escape. Do not add a separate egg wash.

Bake at 175°C for about 90–110 minutes. The top should be golden brown, edges clearly bubbling and center firm without liquid ripples when the pan is gently moved. A thin knife inserted into the center should pass through soft apples and set layers without raw sour cream mixture. If the top browns early, loosely cover with aluminum foil after about 45–60 minutes. Do not use the broiler. Moist poppy seeds and curd cheese will not give a dry-skewer result.

Set the pan on a rack and cool for about 1–1½ hours, until no longer steaming heavily. Then cover and refrigerate for at least 6 hours, preferably overnight, until completely cold in the center too. Do not leave the cake on the counter overnight. Do not remove it hot from the pan or press it down with a weight. The fillings will set during chilling.

Cut the cold cake along the earlier scores into 24 pieces in a 4 × 6 grid. Lift out with a wide spatula, removing parchment beneath each portion. Serve the edges too; do not trim anything. No powdered sugar, extra walnuts or cream. Keep covered in the refrigerator for up to 3 days. Before serving, you may leave portions out for about 20 minutes so they are not refrigerator-cold. Each of the four fillings appears twice in the cross-section.