Beat the sugar and eggs together. Add vanilla and 1 to 2 teaspoons gingerbread spice mix, then zest the piece of orange into the mixture. Stir in the cooled, melted butter, then add the flour mixed with baking powder.

Grease your muffin tins. Spoon in half the batter, add a small amount of jam or a piece of candied kumquat as a filling, then cover with the remaining batter.