Beat egg whites with sugar as on meringue, add cocoa at the end, mix + nuts and gently mix with proteins.
Cover a baking sheet 30 * 40 with baking paper, put the meringue and level. Place the baking sheet in an oven preheated to 150 degrees. Bake the meringue with nuts for 30 minutes, then another 30-50 minutes (depending on the oven and readiness) at the lowest temperature.
Take out the cake, let it cool, remove the paper.
Cream:
Melt chocolate, butter and cocoa.
Add cognac, cool for 5-10 minutes.
Assembly:
Cut the meringue cake with nuts into 3 parts, anoint each cake with cream, press the cake well, sprinkle the top with crumbs from the cake.
Cut the cake into squares with a sharp knife. It turns out 12 petit fours.