Preheat oven to 350 degrees. Coat a 9x13” baking dish with cooking spray and set aside.
In a medium bowl, add oats, flour, sugar, and salt and mix to combine. Add in chopped butter and mix in with a pastry cutter or your fingertips until mix forms clumps with pressed together.
In a large bowl, add berries. Mix in sugar, orange juice, and vanilla. Sprinkle with flour and toss to coat.
Scrape the berry mixture into the prepared baking dish and then top evenly with the oat crumble mixture.
Bake for about 45 minutes or until the top is golden and the filling is bubbling.