Heat a grill to medium-high heat.

In a medium bowl, combine the bell peppers, onion, zucchini, mushrooms, chili powder, cumin, and olive oil. Mix until the vegetables are evenly coated.

Place the vegetables on the grill and cook for 5-7 minutes, or until the vegetables are tender and lightly charred.

To assemble the quesadillas, place a tortilla on a flat surface. Sprinkle 1/4 cup of cheese on one half of the tortilla, top with the grilled vegetables, and sprinkle with an additional 1/4 cup of cheese. Fold the tortilla in half.

Carefully place the quesadilla on the grill and cook for 3-4 minutes, flipping halfway through, or until the cheese is melted and the tortilla is golden and crisp.

Repeat with the remaining ingredients.

Cut the quesadillas into wedges and serve immediately.