- Heat the oven to 400°F.
Melt the butter: In a small saucepan (or in a small bowl over low heat in the microwave) melt 1 tablespoon of butter. Once cooled add 1 tablespoon brown sugar and 1/2 teaspoon cinnamon. Set aside.
Peel the apples to remove all the skin.
Slice the apples in half from top to bottom.
Core the apples: Use a melon baller or spoon to remove the apple cores.
Cut slices in the apples, leaving the bottom intact: Place the apples cut-side down on a cutting board. Cut slices into the apple, 1/4-inch apart, stopping just before you cut through the bottom. (This keeps the slices connected at the bottom of the apple.)
Brush the apples with melted butter and sugar: Stir together the butter mixture. Use a pastry brush to spread the butter mixture over top of the apples and into the slices.
Bake the apples: Spray a thin layer of cooking spray over the inside of a baking dish. Place the apples in the baking dish, flat-side down. Cover the baking dish with tinfoil, and bake for 20 minutes.
Prepare the streusel: Cut the remaining tablespoon of butter into cubes. Add it to a bowl, along with 2 tablespoons brown sugar, 1/4 teaspoon cinnamon, flour, oats, and a pinch of salt. Use your fingers or a fork to blend the ingredients together.
Top the apples with streusel: After the apples have finished baking, remove the baking dish from the oven. Use a fork to carefully spread the streusel over top of the apples. Work the streusel between the slices as well.
Increase the oven temperature and continue baking: Increase the oven temperature to 425°F. Place the baking dish back in the oven and bake, uncovered, for 15 minutes more.
Cool the apples: Remove the baking dish from the oven. Cool the apples for about 5 minutes before serving.
2 large, firm apples
3 tablespoons unsalted butter, divided
3 tablespoons brown sugar, divided
3/4 teaspoon cinnamon, divided
1 tablespoon flour
1 tablespoon rolled oats
Ice cream, for serving (optional)