Cream egg and sugar with the whisk of the hand mixer. Mix flour, cocoa and baking powder and stir into the egg with the milk. Line a baking tray with baking paper, place a square cake frame (approx. 15 x 30 cm) on top.
Pour the dough into the frame, smooth it down and bake in a preheated oven (electric cooker: 175 °C/ convection oven: 150 °C/ gas: see manufacturer) for approx. 15 minutes. Remove and let cool on a cake rack.
Chop the chocolate coating finely and melt over a warm water bath. Mix the egg yolks and icing sugar with the whisk of the hand mixer until creamy. Whip the cream until stiff. Stir the couverture into the egg yolk and fold in the cream.
Use a cookie cutter (7 cm Ø) to cut 8 circles from the sponge cake. Place 8 portion rings next to each other on a tray, insert 1 sponge cake circle each and spread the chocolate mousse on top.
Chill for 2 hours.
Finely chop the pistachios in a universal chopper. Knead pistachios with marzipan. Sort raspberries. Carefully remove the tartlets from the rings. Press the marzipan through a garlic press and spread on the tartlets.
Decorate with raspberries.