3 1/2 cups sliced nectarines 1/2 cup raspberries 1/2 cup blueberries 2 tsp lemon juice 1 1/2 Tbsp sugar 1 1/2 Tbsp brown sugar 1 1/2 Tbsp cornstarch 1/8 tsp cinnamon pinch of salt Biscuit Topping 3 Tbsp unsalted butter 1 cup flour 2 Tbsp sugar 2 tsp baking powder 1/4 tsp cinnamon 1/8 tsp salt 6 Tbsp low-fat buttermilk 1/2 tsp vanilla extract 1/2 Tbsp Turbinado sugar Preheat gas or charcoal grill to medium (or preheat oven to 400°F) and grease a 10-inch skillet. For the filling, combine nectarines, raspberries, blueberries, and lemon juice in a medium bowl. Add sugars, cornstarch, cinnamon, and salt; toss mixture to coat. For the biscuit topping, cook butter in a heavy saucepan over medium heat, stirring constantly until it foams, turns clear, and then turns a deep brown, about 6 minutes. Set aside. Whisk together flour, sugar, baking powder, cinnamon, and salt in a medium bowl. Add brown butter, buttermilk, and vanilla; stir just until moist. Lightly flour hands and knead mixture 3 or 4 times in the bowl, just until dough comes together. Spoon filling into skillet; top with spoonfuls of biscuit dough and sprinkle with turbinado sugar. Grill over indirect medium heat (400°F) with the lid closed for about 25 minutes (or bake about 20 minutes) until juices are bubbling and biscuit topping is golden. Let cool slightly on a wire rack before serving. Store leftovers covered in the refrigerator; warm before serving.