Cranberry Upside-Down Cake

Preheat oven to 350°F.

Heat brown sugar and 2 tablespoons each butter and orange juice in a large ovenproof skillet, preferably cast-iron, over medium heat, stirring constantly, until the butter melts and the mixture starts to bubble, about 3 minutes. Let cool for 5 minutes. Coat the sides of the pan with cooking spray.

Bring the remaining 1/4 cup orange juice and cranberries to a simmer in a medium saucepan over medium heat, stirring often, until about half the cranberries have popped, about 5 minutes. Pour evenly over the cooled sugar mixture in the pan.

Whisk whole-wheat flour, all-purpose flour, baking powder and salt in a medium bowl.

Separate egg whites and yolks. Place the yolks in a large bowl and add the remaining 2 tablespoons butter, oil, granulated sugar and vanilla. Beat with an electric mixer on medium-high speed until light and fluffy. Stir in the flour mixture alternately with milk, using a rubber spatula, starting and ending with the flour. Stir just until the flour is incorporated.

Beat the egg whites in a clean dry bowl with clean dry beaters on medium-high speed until they hold soft peaks. Stir one-third of the egg whites into the batter, then gently fold in the rest until almost no white streaks remain. Spread the batter over the cranberries.

Bake until the top is golden brown and the cake pulls away from the sides of the pan, 30 to 40 minutes. Let cool in the pan on a wire rack for 15 minutes. Run a knife around the edge of the pan and carefully invert the cake onto a serving plate. Let cool for at least 30 minutes more before serving. Serve warm or at room temperature. Garnish with whipped cream, if desired.