Preheat the oven to 325 degrees.
Core, peel, and chop the apples and pears into small pieces.
Mix the chopped apples and pears in a large bowl with the cinnamon, sugar, and cornstarch.
Add the apple-pear mixture to a seasoned cast-iron skillet (or a small casserole dish).
In another bowl, mix the oats, brown sugar, flour, and melted butter. Once combined, spread the oat mixture on top of the sugared apples and pears.
Place in the oven and bake for 45 minutes.
Serve warm with scoops of ice cream.