1/2 cup butter or margarine, softened
1 cup sugar
1/2 cup sour cream
1/2 cup orange juice
2 tablespoons grated orange peel
2 cups all-purpose flour
1 teaspoon baking powder
1/2 teaspoon baking soda
3 (1 ounce) squares bittersweet chocolate
In a mixing bowl, cream butter and sugar. Add eggs, one at a time, beating well after each addition. Beat in the sour cream, orange juice and peel. Combine the flour, baking powder, baking soda and grated chocolate; stir into creamed mixture just until moistened. Fill paper-lined muffin cusp three-fourths full.
Bake at 205 degrees C for 15-20 minutes or until a toothpick comes out clean. Cool for 5 minutes before removing from pans to wire racks.