Marinate pineapple rings in rum overnight. Preheat oven to 350°F. Melt the butter and brown sugar in a large iron skillet (at least 12"), or other heavy, oven-proof pan. Arrange the marinated pineapple rings in the bottom of the pan in a single layer and simmer slowly over low heat in the melted butter and sugar until the cake batter is ready to go into the pan.
Mix the granulated sugar, reserved pineapple juice and egg yolks in a large bowl. Sift the flour, baking powder and salt in a separate bowl. Beat egg whites until peaks form. Quickly mix flour mixture into the sugar and egg mixture until well blended. Gently fold in egg whites.
Place one cherry half upside down in the middle of each pineapple ring. Sprinkle chopped macadamia nuts evenly over the rings, gently spoon the batter over the pineapple rings and macadamia nuts.
Bake for 20-25 minutes, or until a toothpick comes out clean. Let the cake cool until it is just warm to the touch, then invert over a large plate. Serve warm or at room temperature. Makes 8 servings.
Approximate Nutrient Analysis per serving:
500 calories, 20 g fat, 9 g saturated fat, 110 mg cholesterol, 250 mg sodium, 70 g carbohydrate, 1 g fiber, 55 g sugar, 5 g protein