Preparation

• Preheat the oven to 350°F (175°C) and set an oven rack in the middle position. Grease a 9-inch (23-cm) springform or regular cake pan with butter or nonstick cooking spray. If using a regular cake pan, line the bottom with parchment paper and grease again.
• In a small bowl, whisk together the flour, baking powder and salt.
• Using a mixer, cream the butter and granulated sugar until light and fluffy, about 3 minutes. Add the eggs one at a time, mixing well after each. Beat in the vanilla and rum. Add the flour mixture and mix on low speed until just combined. Fold in the chopped apples.
• Scrape the batter into the prepared pan and even the top. Sprinkle with 1 tablespoon of granulated sugar. Bake for about 40 minutes, or until golden and a toothpick inserted in the center comes out clean.
• Allow the cake to cool on a rack in the pan. Once cool, run a knife around the edges. If using a springform pan, remove the sides. If using a regular pan, carefully invert the cake onto the rack, remove parchment paper, then flip the cake over onto a platter. Dust with confectioners' sugar if using. Serve warm or at room temperature.