Preheat the oven to 350°F.
Peel, core and evenly slice the apples. Toss with lemon juice.
Place the apples into a 8x8-inch baking dish.
In a small bowl, combine white sugar, brown sugar, cinnamon, corn starch and toss with the melted butter. Set aside.
To make the topping, in a small bowl, mix flour, sugar and butter together with a pastry blender until thoroughly mixed and in tiny crumbles.
Toss the apples with the cinnamon mixture. Make sure they are all well coated.
Spread the topping evenly over the apple mixture.
Cook for 45 minutes until topping begins to brown and the apple mixture is bubbling.
Remove from oven. Allow to cool for 15-30 minutes. Juices will thicken up.
Serve with a scoop of vanilla ice cream or whipped cream.