Unroll pie crust onto work surface. Using rolling pin, roll out pie crust into 12-inch round. Using 2 1/2-inch round cookie cutter, cut 24 rounds from pie crust, rerolling scraps if needed. Press 1 pastry round into each of 24 ungreased mini muffin cups. Spoon 1 teaspoon of the dulce de leche (reserve 2 tablespoons) in each cup.