This homemade gluten-free rhubarb crisp has an oat and brown sugar topping! The rhubarb turns sweet and jammy in the oven. Easy to make and can be baked in the oven or on the grill.
Mix all filling ingredients together and let sit while preparing the crisp topping.
In a separate bowl, whisk together all topping ingredients, everything but the butter. Then stir in the melted butter, and fully combine.
Add filling to a 9 or 10 inch baking dish or , 10 inch cast iron skillet. Top with crumble, leaving about 1/2 inch gap around the edges so you can see the rhubarb peak through.
Turn on left and middle set of burners of your grill, leaving one side of the grill unheated. Preheat rest of grill to 400 degrees F. When temp holds steady, put the crisp on the side of the grill with no burners on, and cover with foil. Close grill lid. For the grill, Let bake for 20 minutes. Then remove foil, and rotate the pan clockwise. Close lid. Continue to bake for 25-30 more minutes, until bubbling and top is crisp is lightly browned.
To bake in oven, preheat oven to 375 degrees F and bake crisp for 40 minutes, until fruit is softened and bubbling and the top is golden brown.
Let cool for 20-30 minutes before eating with vanilla ice cream.