Preheat oven to 350? degrees F. Generously butter 9-inch-diameter cakepan with 1? inch high sides; line pan with 10-inch-diameter nonstick skillet over medium heat. Add 1/2 cup sugar and cook until sugar dissolves and mixture turns deep golden brown, stirring occasionally, about 6 minutes. Add apple wedges and gently shake skillet to distribute caramel evenly. Cover and cook until apples release their juices, about 5 minutes. Uncover and cook until apples are tender and caramel thickens and coats apples, stirring occasionally, about 13 minutes. Transfer apples and caramel syrup to prepared cake pan,spreading evenly.

Whisk flour, baking powder and salt in small bowl to blend. Place cornmeal in large bowl; pour 1/2 cup boiling water over and stir to blend. Add 6 tablespoons butter and 3/4 cup sugar to cornmeal mixture.Using electric mixer, beat until well blended. Beat in eggs and vanilla. Beat in flour mixture alternately with milk in 2 additions each. Pour batter over apples in pan.

Bake cake until golden and tester inserted into center comes out clean, about 40 minutes. Cool cake in pan 5 minutes. Run small knife between cake and pan sides to loosen cake. Carefully invert cake onto ovenproof or microwavable platter and peel off parchment. Cool 15 minutes. (Cake can be made up to 6 hours ahead. Rewarm in 350F oven about 10 minutes or microwave on medium just until slightly warm, about 2 minutes.)

Cut cake into wedges, place on plates, and serve warm with a scoop of vanilla ice cream.