1For each quesadilla, spread 1 tortilla with 1 tablespoon of the pesto. Top with 1/4 cup of the chicken, 1/4 cup of the spinach and 2 tablespoons of the cheese. Top with a second tortilla.
2Heat heavy skillet over medium heat. Add 1 quesadilla to skillet. Cook about 2 minutes until bottom is lightly browned. Carefully turn; cook 2 minutes longer until second side is lightly browned and cheese is melted. Repeat with remaining quesadillas.
3To serve, cut each quesadilla into 4 wedges.