In a large bowl, combine oats, brown sugar, baking powder, salt, and cinnamon. In another bowl combine eggs, milk, and butter; then stir into the dry ingredients. Stir in apple, peaches, and blueberries.
Grease an 8x8 square baking dish (or appropriately sized vessel) with nonstick spray. Pour the batter into the baking dish. Bake, uncovered, until a knife inserted in the center comes out clean, about 30-40 minutes. Cut into squares.