Hasselback Apples

Choose hard apples with a sweet-tart flavor, such as Pink Lady or Honeycrisp; in our tests, Fuji and Granny Smith apples fell apart.
Preheat the oven to 400 degrees.Starting at the outermost edges, cut most (but not all) of the halves of each apple at 1/8-inch intervals. Place the apple halves, cut side down, in an 8-inch square glass or ceramic baking dish greased with cooking spray. Combine 1 tablespoon sugar, 1 tablespoon butter, and 1/2 teaspoon cinnamon; spread the mixture evenly over the apples.Cover the pan with foil; bake at 400 ° C for 20 minutes. Remove the foil. Bake at 400 ° C for 10 minutes or until apples are tender. Remove the pan from the oven; let cool for 10 minutes.Combine remaining 3 tablespoons sugar, remaining 1 1/2 tablespoons butter, remaining 1/4 teaspoon cinnamon, oat flakes, flour, and salt. Carefully open the apple halves with a fan. Spread the oatmeal mixture evenly over the apples. Bake at 400 ° C for 10 minutes. Turn the grill on high (leave the pan in the oven); bake for 2 minutes. Serve with ice cream.