- 1 cup brown sugar
- 1 tsp baking powder
- 1/4 tsp salt
- 3 cups all-purpose flour
- 1 cup cold unsalted butter
- 1 egg
- 1 cup raw oats
- 3 cups fresh chopped rhubarb
- 12 oz fresh or frozen blackberries
- 1/2 cup white sugar
- 4 teaspoons cornstarch
- Preheat the oven to 375 F, and butter a 9×13 baking dish.
- Combine the brown sugar, baking powder, salt, and flour in a bowl. Mix until incorporated, then cut in the butter and egg with a pastry cutter or forks. Mixture should be crumbly.
- Pat 2/3 of the mixture into the prepared pan. With the remaining 1/3, add the oats and mix to combine.
- In a separate bowl, combine the rhubarb, blackberries, white sugar, and cornstarch. Mix well, then assemble evenly over the prepared crust.
- Pour the remaining crust/oat mix over the fruit.
- Bake for 45 minutes, or until the top is turning golden. Remove and let cool completely before slicing and serving.