Nutrition per serving may change if servings are adjusted.
1 tablespoon butter
1 tablespoon dark corn syrup
½ cup packed light brown sugar
1 small pineapple
2 tablespoons chopped pecans, or walnuts
½ cup pecans, or walnuts
⅔ cup cake flour
1 teaspoon baking powder
¼ teaspoon salt
¼ teaspoon ground nutmeg
2 large egg whites
⅔ cup packed light brown sugar, divided
2 large eggs
1 tablespoon dark rum
1 teaspoon vanilla extract
To make topping: Preheat oven to 375°F. Lightly oil a 10-inch cast-iron skillet.
Heat butter and corn syrup in skillet over medium heat, stirring, until butter melts. Remove from heat. Sprinkle ½ cup brown sugar over the mixture.
Peel, quarter and core pineapple. Cut across into ¼-inch slices. Using the largest, most uniform slices, arrange pineapple on sugar in slightly overlapping circles. (Reserve remaining pineapple for another use.) Sprinkle 2 tablespoons pecans (or walnuts) around the pineapple. Set aside.
To make cake: Spread ½ cup pecans (or walnuts) in a pie pan and bake until fragrant, 5 to 7 minutes; let cool.
Combine the toasted nuts, flour, baking powder, salt and nutmeg in a food processor; process until the nuts are coarsely ground.
Beat egg whites in a large bowl with an electric mixer on medium-high speed until soft peaks form. Gradually add ⅓ cup brown sugar, beating until stiff and glossy (this can take up to 5 minutes).
Beat whole eggs, rum, vanilla and remaining ⅓ cup brown sugar in another bowl with mixer on medium-high speed until thick and pale, about 5 minutes.
Whisk one-fourth of the beaten whites into whole-egg mixture. Gently fold in half the nut mixture, then remaining whites, then remaining nut mixture. Spread the batter over the pineapple.
Bake the cake until top springs back when touched lightly and a skewer inserted in the center comes out clean, 30 to 35 minutes. Let cool in the pan on a wire rack for 10 minutes. Loosen edges and invert onto a cake plate, replacing any topping that may have stuck to the skillet. Let cool for 20 minutes more. Serve warm or at room temperature.