Preheat the oven to 190 degrees and grease the muffin tray well.
Wash and stone the plums and cut into pieces.
Mix the flour, baking powder, baking soda, cinnamon and almonds in a bowl.
Let the butter melt in a saucepan (or in the microwave). Then, in a second bowl, beat the melted butter, sugar, egg, buttermilk and brandy or rum until frothy. Add flour mixture and plums and stir in.
Fill the dough into molds and bake for about 20-25 minutes.