Preheat oven to 425 degrees. Unroll pie crust on a floured surface. Using a 2 inch round cookie or biscuit cutter cut out 24 circles. Place rounds into an ungreased mini muffin tin. Press until it is fully lined. Pinch edges to make a cute edge. Prick bottoms with a fork and bake for 5 minutes or until set.
!To Make the Tarts:
Preheat oven to 350 degrees. In a small bowl, season tomatoes with salt and pepper. In a medium bowl, mix together mayonnaise, Parmesan, Muenster and Havarti. Spoon chopped tomatoes into shells evenly. Top with a dollop of mayonnaise/cheese mixture. Bake for 18-20 minutes. Serve while warm.