This quick-to-fix nectarine dessert starts with biscuit mix.
Heat oven to 425°. Pit and slice 3 of the nectarines and toss together with 1/4 cup of the sugar and the vanilla. Set aside. Peel, pit and dice remaining nectarine.
In a large bowl, combine biscuit mix, remaining 2 tablespoons sugar, milk and butter. Stir in diced nectarine. Drop 1/2-cup mounds onto a heavy-duty nonstick baking sheet.
Bake at 425° for 12 minutes. Cool biscuits on a wire rack. Split one in half horizontally and place bottom on a plate. Top with 1/3 cup of the sliced nectarines and 1/4 cup whipped topping. Place top half of biscuit on whipped topping, and dollop with 1 tablespoon additional topping. Repeat with remaining biscuits, nectarines and whipped topping and serve immediately.