2. Finely grate both types of chocolate.
3. Preheat the oven to 170°C (fan oven).
4. Separate the eggs. Beat the egg whites with a pinch of salt until stiff, so that they become really firm.
5. First, beat the soft butter with the sugar for 5 minutes until fluffy. Then add the egg yolks and cinnamon (optional) and beat for another 5 minutes.
6. Mix flour and baking powder.
7. Measure out 150 ml of the chai tea with oat drink and stir it into the egg mixture.
8. Gradually mix the flour mixture with the egg mixture until you get a smooth dough. Then carefully fold in the beaten egg whites using a whisk.
9. Pour the mixture into the paper baking cups and bake on the middle shelf for about 20 minutes.
11. Put the icing sugar in a bowl and mix with the remaining chai tea until smooth. Brush onto the cooled muffins and decorate with chocolate or other decorations.