Step 1Toss together apples and lemon juice to coat slices. Stir in 2 tablespoons brown sugar and 1 teaspoon cinnamon. Spoon apples into lightly buttered 8-inch-square baking dish.
Step 2Combine flour, oatmeal, remaining brown sugar and cinnamon. Using your fingers, work butter into oat mixture until evenly blended. Spoon crunch topping evenly over apples.
Step 3Bake at 375 degrees until apples are tender and topping is lightly browned, about 30 minutes. Cool slightly, then serve.