Preheat the oven to 400 degrees F (200 degrees C). Grease a 12-cup muffin tin or line cups with paper liners.
Combine butter and sugar in a bowl and beat with an electric mixer until creamy. Add eggs, one at a time, and beat until well combined. Mix in milk and vanilla sugar.
Combine flour, baking powder, and salt in a small bowl. Sift over the batter and fold in with a spatula until combined. Fold apples, almonds, and crumbled marzipan into the batter.
Spoon the batter into the prepared muffin cups.
Bake in the preheated oven until tops spring back when lightly pressed, 15 to 20 minutes. Cool in the tin for 5 minutes. Transfer to a wire rack to cool completely.