Preheat the oven to 350 degrees. Spread 2-3 tablespoons of the pesto sauce onto each flattened chicken breast. Place one slice of cheese over the pesto. Roll up tightly, and secure with toothpicks. Place in a lightly greased baking dish.
Bake uncovered for 45-50 minutes in the preheated oven, until chicken is nicely browned and juices run clear.