Place the diced apples in a small ramekin or other oven-safe dish. Stir in the sugar and the cinnamon.
FOR THE TOPPING
In a small bowl, whisk together the brown sugar, flour, cinnamon and butter. Cut the butter into a few pieces and toss them into the dry ingredients. Using your fingers or a fork, work the butter into the dry ingredients until heavy crumbs are formed.
Spoon the crumb mixture over the apples.
Bake for 25 minutes or until apples are soft.
You could substitute pears in the recipe for a lovely pear crisp.