Preheat the oven to 350℉.
Prep the topping, using some sort of masher, cut the butter into the brown sugar, flour, cinnamon and salt. When done, fold in the oats.
Once the fruit is prepped, toss the fruit in the cornstarch, sugar and vanilla. Add the fruit into the bottom of the baking dish. Now, top it with the topping you made first. Place the baking dish in the oven and bake for 35-45 minutes or until the top has turned a golden brown.
Remove from the oven. You can serve this warm but allow it to cool 15-20 minutes first so they top can crisp and harden up before serving. Best served with a scoop of ice cream, enjoy.