1. Preheat oven to 350°.
2. To prepare topping, lightly coat a 9-inch round cake pan with cooking spray. Heat brown sugar and 2 tablespoons butter in a small saucepan over medium heat. Cook 2 minutes or until butter melts and sugar dissolves, stirring occasionally. Pour sugar mixture into prepared cake pan, tilting pan to coat bottom evenly. Arrange cranberries evenly over sugar mixture.
3. To prepare cake, weigh or lightly spoon flour into dry measuring cups; level with a knife. Combine flour, baking powder, and salt; stir with a whisk. Place granulated sugar and 1/2 cup butter in a bowl; beat with a mixer at medium speed until well blended and fluffy (about 3 minutes). Add egg yolks, 1 at a time, beating well after each addition. Beat in vanilla. Fold flour mixture into sugar mixture alternately with milk, beginning and ending with flour mixture.
4. Beat the egg whites with a mixer at high speed until stiff peaks form using clean, dry beaters. Gently fold the egg whites into the batter. Spoon the batter over the cranberries, spreading evenly. Bake at 350° for 55 minutes or until a wooden pick inserted into center of the cake comes out clean. Cool in pan 15 minutes on a wire rack. Loosen cake from sides of pan using a narrow metal spatula. Place a serving plate upside down on top of cake, and invert the cake pan onto the plate. Let stand 5 minutes, and remove the pan. Serve warm.