Special equipment: four 4-inch tart pans
Heat oven to 375° F. Coat the bottom and sides of the tart pans with cooking spray, vegetable oil, or butter. Divide the piecrust into 4 portions and roll them out so they're slightly larger than the pans. Press the dough into the pans. Run a rolling pin over the tops to trim the excess dough. Line the dough with parchment paper or foil, fitting it up the sides. Fill with pie weights, dried beans, or uncooked rice. Place the pans on a baking sheet and bake for 10 minutes. Remove the weights and paper and let cool.
Meanwhile, in a saucepan, over medium heat, cook the berries, sugar, water, cornstarch, and cinnamon until the sauce thickens slightly, 5 to 6 minutes. Remove from heat and cool slightly. Remove the crusts from pans and transfer to serving plates. Place 1/2 pint of ice cream in each tart. Spoon some sauce on top.
Tip: If you don't own small tart pans, make one large pie using the same recipe.