Place 2 paper baking cups inside each other in the recesses of a muffin tray (12 recesses). Preheat oven (electric cooker: 175°C/circulating air: 150°C/gas: level 2). Mix flour, baking powder and baking soda.
Whisk the egg in a large bowl. Add sugar, vanilla sugar, oil, buttermilk, lemon peel and 1 tbsp. lemon juice, mix well with a wooden spoon.
Add the flour mixture and stir only briefly so that all ingredients are mixed. Spread the dough evenly into the moulds. Bake in a hot oven for 20-25 minutes. Let the muffins cool down in the baking tray for about 10 minutes.
Remove and let it cool down.
Warm the jelly and cool slightly, but do not let it set. Mix cream cheese, 1 tablespoon lemon juice and icing sugar with the whisk of the mixer for a short time. Set 1/3 of the cream aside. Stir the jelly into the rest of the cream.
Spread white cream on 6 muffins. Decorate with chocolate lentils and sugar writing as eyes. Fill pink cream into a piping bag with a very small perforated nozzle. Spray as brains on the remaining 6 muffins.
Chill for at least 1 hour.