Let Puff Pastry Sheet thaw slightly, making it easier to unfold and manipulate.
Spread the pesto sauce onto the puff pastry sheet, then cut into about 16 pieces. I find this easiest with a pizza cutter!
Prep mini-muffin pan by adding cooking spray into each of the cups.
Place each square into one of the cups. I usually stretch each square just a little before putting them into the cup.
Add 2-3 tomatoes pieces and 1-2 pieces of mozzarella into each up. Garnish with basil if desired!