Preheat oven to 425°F. Lightly grease a large sheet pan.
In a bowl, combine black beans, corn, bell pepper, zucchini, and red onion. Add taco seasoning and olive oil. Toss to coat.
Place 3 tortillas on the prepared sheet pan, overlapping slightly if needed.
Sprinkle half the cheese evenly over the tortillas. Spread vegetable mixture on top, then sprinkle with remaining cheese.
Top with the remaining 3 tortillas. Spray the top tortillas lightly with cooking spray.
Place another sheet pan on top to weigh down the quesadillas.
Bake for 15-20 minutes until tortillas are golden and crispy.
Remove from oven, let cool slightly, then cut into triangles.
Serve with salsa, guacamole, and sour cream.
Notes
Swap in your favorite veggies or add cooked chicken for extra protein. These quesadillas are perfect for meal prep and make great leftovers for lunch the next day. Serve with salsa, guacamole, or sour cream.