This really is a time taking effort, you need at a least a day to make it but it worth all effort. This recipe is adapted from Joe pastry and stabilized chocolate mousse inspired from here. This recipe makes about six 2 ½ inch pieces.
- Preheat your oven to 350. Line a 8 inch square pan with parchment paper and brush it with melted butter.
- For the cake: Whisk together the cocoa powder and flour.
- Add the chocolate pieces and butter in a bowl and stir to melt, apply ten-second bursts of heat as necessary. When the mixture is smooth, set it aside to cool.
- In a mixer fitted with a whip, beat the egg yolks on high until pale and thick, about five minutes, then with the machine running add half the sugar in a stream.
- Continue whipping until the yolks and sugar fall from the whip in a ribbon.
- Transfer the yolk mixture to a medium bowl and fold in chocolate mixture. Set the bowl aside while you prepare the whites.
- Rinse and dry the mixer bowl and whip (If you have a second bowl like I do place it in the freezer while you do the above steps). Put the whites in the bowl and whip to soft peaks, add the salt, then add the remaining sugar in a stream.
- Continue to whip to the stiff peak stage, the foam should be very glossy. Stir 1/3 of the whites into the yolk mixture to lighten the batter, then fold in the rest in two additions. Lastly, fold in the flour and cocoa.
- Scrape the batter into the prepared pan and level it with an icing spatula. Bake for 12-15 minutes.
- Remove the cake from the oven and loosen the edges with a knife.
- Lay a second sheet of parchment and a wire rack over the layer, then invert the pan. Remove the pan and — carefully — the top sheet of parchment.
- Cover the cake with a clean kitchen towel and another wire rack and invert the cake again. Remove the parchment from the top and allow the cake to cool.
- When the cake is cool, cut the sheet in half.
- Prepare the glaze by combining all the ingredients except for the vanilla in a microwave-safe bowl. Heat the bowl for 20 seconds on full power, then apply as many ten-second bursts as needed to melt the chocolate completely, stirring in between to allow the residual heat to do most of the work.
- Stir in the vanilla and pour the glaze over the cake, spreading it promptly with an icing spatula. Allow the glaze to set, about 45 minutes to an hour.
- Divide into two equal halves, cut one half into 2 ½ inch 6 pieces. .Set the pieces aside or store in the refrigerator.
- For the filling: melt the chocolate pieces with 1 tablespoon heavy cream in the microwave, using a 20-second burst, then as many ten-second bursts as needed until it’s completely smooth. Cool it until it’s just barely warm to the touch.
- Add ¾ teaspoon gelatin in 1 tablespoon cold water and set aside for 5 minutes.
- Then add 1 tablespoon of boiling water into the gelatin.
- Add this liquid gelatin to 3/4 cup heavy cream along with rum extract, vanilla and whip very well.
- Stir together the cocoa and powdered sugar.
- Whip the cream mixture to just shy of soft peaks. Then, with the machine on, whip in the cocoa and sugar mixture.
- Add the melted chocolate all at once and quickly whip or whisk it in, whichever works better for you.
- Set the second cake layer on sheet of parchment paper and trim up the sides. Brush apricot glaze over it, then apply the filling, being careful to apply it evenly.
- Square up the corners.
- Gently lay the glazed top pieces on the top, then refrigerate the entire cake for at least an hour.
- When ready to serve, cut the cake into pieces using a sharp knife heated under hot top water.
- Enjoy