Preheat oven to 350 °F.
Place the diced eastern cantaloupe into a bowl and add the next four ingredients. Mix together.
In a separate bowl, add oats, flour, brown sugar, baking powder, and cinnamon.
Melt ½ cup of butter and add to the oat and flour mixture. Mix together until the mixture resembles sand.
Pour the cantaloupe mixture into a baking dish and cover with the crumble topping.
Bake for 35 minutes or until the top is golden and the filling is bubbling.
Serve with scoops of vanilla ice cream.