Preheat oven (electric cooker: 175°C/circulating air: 150°C/gas: see manufacturer). Place 1 paper baking tin in each of the recesses of a muffin tray (12 recesses).
For the muffins, briefly mix eggs, sugar, vanilla sugar, oil and sour cream with the whisks of the mixer. Mix flour, baking powder and nuts and fold in briefly. Spread the dough evenly into the bowls.
Bake in a hot oven for 20-25 minutes. Let it cool down.
Chop the chocolate and melt in a hot water bath. Place baking paper on a board or tray (should fit in the refrigerator). Pour chocolate into a disposable piping bag or freezer bag.
Spray 24 small circles (2-3 cm Ø) onto the baking paper. Place 1 brown chocolate flake as a pupil on each circle. Allow to set.
Cut a wedge into each of the round muffin surfaces for the mouth and insert 1 biscuit each.
Stir icing sugar, cream cheese and food colouring (1-2 knife tips) with the whisks of the mixer until smooth, until the mixture is blue. (Attention! Colours very intensively.) Possibly re-colour.
Pour into a piping bag with a small star-shaped spout. Spray small fringed tuffs all around the muffins, partly on top of each other. Keep cold until the surface is firm. Just before serving, stick the chocolate eyes into the cream.