Cut the chocolate into pieces. Melt butter and 30 g of chocolate in a hot water bath. Put the muesli in a freezer bag and crumble it coarsely with the dough roller. Mix muesli and butter mixture. Grease eight tartlet cups with lifting base (each approx. 10 cm Ø) with oil. Press the crumb mixture into them to form a firm base. Keep cold.
Heat 200 g cream. Melt the rest of the chocolate and mint bar in it. Pour into a bowl, cover and chill for about 2 hours.
Whip 200 g cream until stiff, chill. Whisk the chocolate mixture with the whisk of the mixer for about 2 minutes until creamy. Stir the whipped cream in streaks into the chocolate cream.
Remove the cake bases from the moulds. Spread the chocolate mousse in them and chill for about 30 minutes. Sort the raspberries. Wash the mint and pluck the leaves from the stems. Decorate the tartlettes with raspberries and mint and dust with cocoa.