Thaw fruit if frozen. In a medium saucepan, combine fruit, sugar and cornstarch. Cook and stir over medium heat until thickened and bubbly. Keep hot.
For topping, mix biscuit mix, walnuts, brown sugar and cinnamon. Stir in milk until moistened. Transfer hot fruit to 8x8 foil or metal pan. Spoon topping into mounds on fruit filling.
Place pan in center of grill for 20-25 minutes or until topping is lightly golden brown and a toothpick inserted comes out clean. Serve warm with vanilla ice cream.
I've used peaches, raspberries, strawberries, rhubarb etc. Sometimes I mix the fruit.
May use crisp topping from apple crisp for additional topping.
See this recipe for topping: Apple Crisp on the Grill