Preheat oven to 375°F. Lightly oil a 9-inch glass pie plate or 8 x8 baking dish.
To make the crisp topping, combine all the ingredients in a bowl and mix to combine so that it resembles coarse crumbs.
In another bowl, combine the peaches and blueberries with the cornstarch and mix to distribute the cornstarch. Tip: I find it easier to distribute the corn starch using my hands.
Plate the fruit in the greased pie plate and top with the crisp oat topping distributing it evenly over the fruit.
Bake for 35-40 minutes until the topping is golden brown.
Serve it on its own warm, with vanilla ice-cream for dessert or Greek yogurt for breakfast.
