Preheat your oven to 400 degrees Fahrenheit.
Prepare the cobbler crust per the instructions (or whip up my perfect pie crust recipe). Wrap the dough in plastic wrap and refrigerate it while you make the fruit filling.
Add the chopped rhubarb and strawberries to a glass bowl. Add the brown sugar and corn starch. Mix well to combine.
Pour the strawberry/rhubarb mixture into a cast iron pan or other heavy-duty pan.
Use a rolling pin to flatten the cold cobbler dough into the shape and size of your pan, then tear it into big pieces and place on top of the fruit mixture.
Bake the cobbler for 35-45 minutes. Allow the cobbler to cool for 20-30 minutes before serving.
If you'd like to make your own crust, check out my perfect pie crust recipe. You can add 1/3 cup of granulated sugar, 1 teaspoon of vanilla extract, and a 1/2 teaspoon of ground cinnamon to the pie crust recipe to make this delicious crust from scratch!