6 tablespoons cold unsalted butter, cut into cubes
Vanilla ice cream, optional, for serving
The Steps
Preheat your oven to 375°F.
Make the filling. In a large bowl, add raspberries, rhubarb, lemon zest and juice, sugar, and cornstarch. Toss to combine. Spread evenly into bottom of your Stargazer Cast Iron skillet.
Make the topping. In another bowl, combine flour, oats, light brown sugar, cinnamon, and salt. Add butter and using your fingers, mix until you have large crumbles.
Scatter the topping evenly over fruit, covering it completely.
Bake for 30-35 minutes, until fruit juices are bubbling around outside edges. Place under the broiler for 1-2 minutes to brown top. Allow to cool before serving.