1. Preheat oven to 375 degrees and set a 10 inch cast iron pan or 9 inch square baking dish aside.
  2. Place fruits in a medium bowl and sprinkle with cornstarch and sugar. Stir gently to combine and let sit until topping is made.

TO MAKE TOPPING:

  1. In a small mixing bowl, place egg, oats, flour, sugars, and cream.  Using a fork, combine until the mixture is the texture of coarse meal.
  2. Pour the fruit mixture into the pan and sprinkle crumble topping evenly over the top of the fruit mixture.
  3. Drizzle melted butter over the top of the crumble topping.
  4. Bake for 40 minutes or until browned and bubbling. Let sit for at least 15 minutes before eating.
  5. Serve with ice cream if desired.