Rigó Jancsi

Ingredients

• 4¼ ozfloursifted, for the sponge
• 1⅓ ozcocoa powderunsweetened, for the sponge; also used to flavour the cream
• 5¼ ozsugargranulated or icing sugar for the sponge
• 4eggfor the sponge
• 1 tspbaking powderfor the sponge
• ½ tspBaking sodaonly in the kefir version of the sponge (optional)
• 1 pinchsaltfor the sponge and the chocolate cream
• ¼ cupoilfor the sponge
• 3⅛ ozKefirbuttermilk works too, for the stirred sponge (optional)
• ¼ cupwaterfor the stirred sponge (optional)
• 10½ ozdark chocolateat least 55 % cocoa, for the cream and the coating
• 2½ cupsCreamat least 30 % fat, ice cold
• 1¾ ozbuttermelted for the sponge and for the glaze (optional)
• 2 tspvanilla sugarto sweeten the cocoa cream (optional)
• 3½ ozjamtart fruit jam such as strawberry, orange or blueberry, spread on the bottom layer (optional)
• 2 tbsprumto flavour the whipped ganache (optional)
• 1 tbspgelatinbloomed in water, to stabilise the cream (optional)

Method

1. Heat the oven to 175–355 °F and line a baking sheet with parchment. Sift the flour, cocoa powder, baking powder (plus the baking soda if you're making the kefir version) and a pinch of salt together.
2. Beat the eggs with the sugar until thick and foamy — or, for the stirred version, whisk the kefir, water and a single egg with the sugar. Fold in the sifted dry ingredients gently, then fold in the sunflower oil or melted butter.
3. Spread the batter thinly and evenly across the sheet and bake for 7–12 minutes. Let it cool completely, then peel off the parchment, trim the edges square and cut the sponge into two equal sheets.
4. Melt the dark chocolate over a water bath. Spread a thin layer of it over the top sheet of sponge and let it set in the fridge.
5. Whip the ice-cold cream slowly to soft peaks — don't take it too far. For the chocolate cream, stir a third of the cream vigorously into the chocolate once it has cooled to 32–95 °F, then fold in the rest in two additions. For the cocoa version, simply fold the cocoa powder and vanilla sugar into the cream instead.
6. Spread the bottom sponge with jam if you like, then pile on the cream in a thick, even layer and smooth out any air pockets.
7. Cut the chocolate-coated top sheet into equal squares with a hot, dry-wiped knife and lay it over the cream. Chill for 2–4 hours, until the cream is firm.
8. Cut into cubes along the marked lines with a hot, dry knife, wiping the blade after every cut.

Tips and variations

You can also make the sponge as a stirred batter with kefir, water, oil and just one egg; butter in place of oil gives it a rounder flavour. For an extra-creamy filling, make a ganache the night before from hot cream and chocolate, chill it overnight and whip it with icing sugar, rum and bloomed gelatine — the gelatine keeps the cream in shape even at room temperature. A tart jam under the cream, strawberry, orange or blueberry, brings a welcome bit of acidity. If you prefer, leave the top sheet plain and pour chocolate glaze over the finished cake at the end instead — or spread the top with plain whipped cream held back for the purpose and decorate it with fruit or chocolate shavings. To serve, set the cubes on small plates, with a little chocolate sauce if you like.