Peel, core, and slice apple crosswise into 7 (1/4-inch) rings. Combine apple rings and brown sugar in a bowl; toss gently. Let stand 5 minutes. Arrange apple mixture in a single layer in a 10-inch cast-iron skillet coated with cooking spray. Bake at 350° for 15 minutes. Combine 1/4 cup sugar, oil, and egg in a large bowl; beat 2 minutes at medium speed of an electric mixer. Add molasses; beat an additional 2 minutes. Combine flour and next 5 ingredients. With mixer running at low speed, add to sugar mixture alternately with hot water, beginning and ending with flour mixture. Spoon batter over apple rings. Bake at 350° for 30 minutes or until a wooden pick inserted in center comes out dean. Cool in skillet 10 minutes; invert onto a serving plate.