Preheat oven to 350°. In a bowl, combine butter, granulated sugar, almond paste, and orange zest. With a mixer on high speed, beat until mixture is blended, about 2 minutes. Add eggs and beat until fluffy, 1 or 2 minutes. Add flour, stir to mix, then increase speed and beat until well blended. Batter will be thick.
Fill a pan of 12 buttered or paper-lined muffin cups (1/2-cup capacity) about 2/3 full with batter. With a small flexible spatula, spread batter smooth. Arrange a few blackberries on top of batter in each cup; lightly press berries into batter.
Bake until cakes are golden brown, 25 to 30 minutes. Cool in pan about 5 minutes. Serve dusted with powdered sugar.
Note: Nutritional analysis is per serving.