Preheat oven to 350°.
Peel plantains; diagonally cut into 1/2-inch-thick slices. Arrange plantain slices in a single layer on a jelly-roll pan coated with cooking spray. Combine orange juice and next 5 ingredients (through nutmeg) in a small bowl; stir with a whisk. Pour juice mixture over plantains. Dot with butter, and sprinkle with salt. Bake at 350° for 30 minutes. Gently turn plantains over using tongs; bake an additional 10 minutes or until lightly browned.