- To make this apple crisp, preheat oven to 375°F.
- Lightly grease 8×8 baking dish with butter.
- Mix chopped rhubarb and apples in a large mixing bowl.
- Pour Red Poppy Belgian-style flanders over fruit.
- Add sugar, cornstarch, and vanilla and stir till sugar and cornstarch are dissolved.
- Pour rhubarb mixture into prepared baking dish.
- Mix remaining ingredients (except butter) together in large mixing bowl.
- Pour melted butter over topping ingredients.
- Mix with your hands until coarse crumbs form and there’s no dry flour at the bottom of the bowl.
- Pour crumb mixture over rhubarb.
- Bake crisp at 375° for 45-50 minutes.
- Top should be golden brown and the fruit mixture should be really bubbly.
- Let stand for at least 10 minutes before slicing.