1. Preheat the oven to 350°F. Spray and flour a 9-inch round cake pan.
2. Cut the orange into quarters without peeling. Remove seeds and pith. In a small bowl, stir together flour, baking powder and salt.
3. Place oranges, sugar, vegetable oil, eggs and milk in the bowl fitted with the ultrablade knife. Launch the P3 pastry program. Gradually add the flour mixture.
4. At the end of the program, pour the mixture into the prepared pan. Bake for 35-40 minutes or until a knife inserted in the center comes out clean. Cool completely.