Heat oven to 400 F. Unfold the pastry sheet on a lightly floured surface. Roll the sheet into a 10 x 15 inch rectangle. Cut the rectangle into 24 squares (2-1/2 inch). Press the squares into 24 mini muffin cups.
Bake for 15 minutes or until the pastries are golden brown.
Press one small meatball into each tartlet shell. Top each with a teaspoon sauce and a teaspoon of cheese. Bake for an additional 5 minutes or until the cheese is melted and the meatball is warmed through.