Preheat oven to 350 degrees. Combine 2 Tablespoons butter and brown sugar; spread evenly in bottom of greased 9-inch round cake pan. Spread cranberries over mixture and set aside.
Combine the flour, baking powder, and salt in a bowl; reserve. In a separate bowl, combine the remaining butter, sugar, and eggs and beat until creamy smooth. Add the reserved dry ingredients, orange juice, milk, vanilla, and zest and beat until well blended.
Pour the batter over the cranberries and bake until golden, about 55 minutes. Run a knife around the outside and turn upside down on a serving plate.
Per serving: 236 Calories, 4g fat (14% calories from fat), 3g protein, 49g carbohydrate, 43mg cholesterol, 242mg sodium.