Preheat oven to 375°F and lightly grease a 9x13-inch baking dish.
In a large bowl, combine strawberries, rhubarb, 1 cup sugar, cornstarch, and vanilla extract. Toss gently and let sit for 10 minutes, then pour into prepared baking dish.
In another bowl, whisk together flour, 1/3 cup sugar, baking powder, and salt. Cut in cold butter using a pastry cutter or fork until mixture resembles coarse crumbs.
Pour in heavy cream and stir just until a soft dough forms. Do not overmix.
Drop spoonfuls of dough over the fruit mixture, leaving some gaps for steam to escape. Sprinkle with coarse sugar.
Bake for 40-45 minutes until topping is golden brown and fruit is bubbling.
Let cool for 15 minutes before serving warm with ice cream or whipped cream.