Gather the ingredients.
Heat the oven to 425 F.
Lightly grease an 8- or 9-inch-square glass pan. Pour fruit into the pan.
In a small bowl, combine oatmeal, flour, nuts, and melted butter. Add the optional tablespoon of sugar if desired, and stir to combine well and until the topping clumps together. Sprinkle over the fruit.
Bake 15 minutes or until golden brown (longer if you have doubled or tripled the recipe). Remove from the oven and serve warm on its own or with sweetened whipped cream or ice cream.
Remove from the oven when the topping is golden brown and serve warm on its own or with sweetened whipped cream or ice cream. Note: Most canned fruits will work. You can add spices that marry well with the type of fruit and packaged oatmeal you've chosen to use. If the instant oatmeal is unsweetened, adding sugar to taste will give the topping a better flavor.