Put the speculoos in a freezer bag and crumble finely with a rolling pin or something similar. Beat the butter with sugar until frothy. Stir in eggs and milk.
Mix the flour, baking powder, baking soda, lemon peel, ground almonds, speculoos, 1 teaspoon cinnamon and a pinch of salt. Add the flour mixture to the egg mixture and stir until all the ingredients are moist.
Fill the dough up to 3/4 of the way into the muffin pan and bake in the oven at 180 ° C (preferably preheat) for about 20 minutes. Let cool after baking.
Then mix the powdered sugar with the rest of the cinnamon and mix with about 2 tablespoons of water to form a thick glaze. Brush the muffins with it and sprinkle with the almonds.