Preheat oven to 400℉. In a large mixing bowl, combine dry ingredients of 3 cups flour, ½ cup granulated sugar, 1 tbsp baking powder and ½ tsp salt.
Grate or cut 12 tbsp of cold butter into small cubes. Incorporate the butter into the dry mixture with your hands until it reaches a mealy texture. Create a well in the dry ingredients and set aside.
In a small mixing bowl or glass measuring cup, combine 1¼ cup whole milk, 1 egg and 1½ tsp vanilla -- whisk until fully mixed.
Pour the wet ingredients into the well of your butter/ dry ingredient mixture. Stir until just combined and a very sticky dough forms.
Prepare your fruit mixture by slicing 1/2 cup of fresh strawberries (save the other ½ to top skillet with after baking) and rough chopping ½ cup rhubarb. Add to a medium bowl and sprinkle with 2 tbsp granulated sugar, toss to coat.
Transfer sticky batter to a 10" skillet (or glass baking dish) and spread out evenly in the bottom of the skillet. Top with strawberry rhubarb mixture and press fruit into the batter.
Bake for 25-30 mins until golden brown. Top with remaining ½ cup fresh strawberries. Serve warm and top with vanilla ice cream