- 01
Preheat the oven to 180°C/365F. Line a 30 x 25 cm (12 x 10-inch) baking tray with parchment paper and spray with nonstick vegetable spray.
- 02
Mix together flour, cocoa, and salt. In another bowl, beat the eggs with sugar until ribbon; after about 7 minutes, the mixture should be pale yellow and foamy. Add dry ingredients to the egg mixture, whisking them in carefully. Spread the sponge batter evenly on the tray. Bake for 8-10 minutes.
- 03
When the sponge is baked, let it cool and cut into two 15 x 25 cm (6 x 10-inch) pieces.
- 04
To prepare the top layer, first, mix the jam with rum and spread it over one sponge. Then, melt the chocolate with oil in a bain-marie or in the microwave. Pour the ganache over the rum-spiked sponge. Refrigerate for about 30 minutes or until the chocolate is set. Slice the ganache-topped sponge into 15 5 cm (2-inch) squares.
- 05
To make the filling, soak the gelatine in water for 5 minutes. Mix the powdered sugar with cocoa. Beat the whipping cream and then mix it well with the gelatine, adding the dry ingredients and vanilla extract. Mix until well incorporated.
- 06
Evenly spread the filling over the bottom sponge, and then finish the cake by assembling the ganache-glazed sponge squares on top of the filling. Refrigerate until the filling is set. Slice the cubes just before serving.