This was easy and came out great! The original recipe is from: https://www.wellplated.com/triple-berry-crisp/
5 tablespoons melted butter
1 1/4 cups old-fashioned rolled oats
3/4 cup 1:1 gluten free baking flour or regular all purpose flour
1/2 teaspoon ground cinnamon
1/2 teaspoon kosher salt
1/3 cup pure maple syrup
5 cups frozen mixed berries
1 tablespoon lemon juice
2 teaspoons pure vanilla extract
1/2 tablespoon cornstarch
In a bowl, melt the butter. Add the oats, flour, cinnamon salt and maple syrup.
In a slow cooker, combine the mixed berries, lemon juice, vanilla and cornstarch. Sprinkle the oat mixture over the top and cook on low for 2 – 3 hours until bubbly.