- 1 large orange, scrubbed
- 1 cup golden raisins
- 8 tablespoons (1 stick) unsalted butter at room temperature
- 1 cup sugar
- 2 large eggs
- 2¼ cups unbleached all-purpose flour
- 1 teaspoon baking powder
- 1 teaspoon baking soda
- ½ teaspoon salt
- 1 cup low-fat plain yogurt or buttermilk
- 1 cup (6 ounces) bittersweet chocolate wafers or chocolate chips
- Preheat the oven to 350°F. Butter and flour a 10-inch springform pan or 9-inch square pan.
- Remove a thin slice from the stem end of the orange and cut the fruit into eighths, leaving the peel on. In a food processor, combine the orange segments and raisins and process until finely ground.
- In a large bowl, cream the butter and sugar with a wooden spoon or an electric mixer until light and fluffy. Add the eggs, one at a time, beating well. Mix in the orange mixture. In a medium bowl, combine the flour, baking powder, baking soda, and salt. Stir to blend. Add the dry ingredients to the creamed mixture alternately with the yogurt or buttermilk in 2 increments, beating until blended. Reserve ¼ cup of the chocolate for the topping and mix the remainder into the batter. Spread evenly in the prepared pan. Sprinkle the reserved chocolate evenly over the top.
- Bake for 35 to 40 minutes, or until the cake is golden brown and a cake tester inserted in the center comes out clean. Let cool in the pan on a wire rack for 15 minutes, then remove the pan sides. Serve slightly warm or at room temperature, cut into wedges.