Heat broiler. Dump the apples from two 12-ounce packages scalloped apples onto a broiler pan or baking sheet. Toss with the grated zest from 1 lemon. Spread the apples in a single layer and broil about 8 inches from the heat for 5 minutes or until bubbly. Meanwhile, heat 1/3 cup rum or 1/2 cup maple syrup in a small saucepan over low heat. Serve the apples warm with vanilla ice cream. Drizzle with the rum or syrup.