Preheat oven to 180 degrees C. Line a 12 cup muffin pan and with paper patty cups.
Melt the chocolate and butter in a bowl set over simmering water. Cool. Stir in the sugar, eggs, sour cream, brandy and spices.
Sift remaining ingredients into a bowl. Add chocolate mixture to dry ingredients and stir until just combined.
Fill patty cups two-thirds full. Bake muffins for 20–25 minutes. Place pan on a wire rack; let muffins cool briefly before serving.
To make sure that the muffins are feather light, do not mix the batter too vigorously. To achieve the best result, mix the liquid and the dry ingredients with a wooden spoon, not with electric beaters. Mixing should be brief and the ingredients only just blended.