Preheat oven (electric cooker: 200 °C/circulating air: 175 °C/gas: see manufacturer). Separate eggs for the dough. Cream 150 g butter, 2 tablespoons sugar and egg yolk with the whisks of the mixer for approx. 4 minutes.
Beat the egg whites until stiff, then pour in 100 g of sugar. Mix flour, almonds, baking powder and cocoa, stir briefly into the butter-egg yolk cream. Fold in the beaten egg white.
Place paper cups in a muffin baking tray (12 trays). Spread the dough inside. Place 1 ball of Rondnoir on each and press it in slightly. Bake in a hot oven for about 20 minutes. Let the cupcakes rest in the pan for about 10 minutes, then take them out and let them cool down.
For the buttercream, whisk 175 g butter and icing sugar with the whisks of the mixer until foamy. Stir in the yoghurt bit by bit. Colour the cream yellow with some turmeric. Pour into a piping bag with a perforated spout or star-shaped spout.
Spray 2 rows of petals around each chocolate ball. Decorate cupcakes with marzipan bees, for example.