Preheat oven to 375 F. In a 10” cast iron skillet, add your sliced strawberries & rhubarb. Pour the maple syrup over top, followed by both sugars & corn starch, stir to fully combine & set aside.
Prepare your cobbler mix. Add the flour & baking powder to a large bowl, whisk until combined. Add your 12 tbsp cold butter, cubed or grated, and combine until fine crumbs with your hands or a pastry cutter. Make a well and your milk + vanilla mixture. Fold in until a wet, sticky dough has formed.
Dollop the sticky mixture in clumps over the filling in the skillet, leaving gaps in between each one.
Bake for 25-35 mins, until golden brown. Allow to cool at least 10 mins before serving. Enjoy warm w a scoop of vanilla ice cream!