Use 2 × 12-hole muffin pans; line with paper cases. Preheat oven to 180°C.
Beat the marzipan, eggs and butter with a wooden spoon until smooth. Gradually mix in the buttermilk, sugar, orange zest and liqueur with a wooden spoon until light and fluffy.
Sift flour and baking powder into a large bowl. Add marzipan mixture; stir until just combined.
Peel orange very thickly so that white pith is removed. Segment the orange and halve the segments.
Place 1 tsp of mixture in each paper case and place a halved orange segment on top. Add more mixture until cases are two-thirds full. Sprinkle with flaked almonds.
Bake for about 20 minutes until golden brown. Place pans on a wire rack; leave muffins to cool.
Try this, too…
To make Chocolate Apple Muffins, replace orange zest and liqueur with 1/2 tsp ground cinnamon, 2 tbsp hazelnut spread and 1/2 tbsp cocoa powder. Peel, halve and core 2 tart apples. Cut into small cubes and stir into the mixture after Step 3. Continue as for the main recipe.