Prep the pan: Heat the oven to 425°F (220°C).
Line a large rimmed sheet pan with parchment or foil for easier cleanup.
Toss the veggies: In a large bowl, add the bell pepper, onion, zucchini, and corn. Drizzle with 1 tablespoon olive oil and sprinkle with chili powder, cumin, smoked paprika, garlic powder, salt, and black pepper. Toss to coat evenly.
Roast for flavor: Spread the veggies on the sheet pan in an even layer.
Roast for 12–14 minutes, until slightly softened and edges begin to char.
Mix in the beans: Transfer the roasted veggies back to the bowl. Add the black beans, lime juice, and cilantro if using. Taste and adjust salt.
Assemble the quesadillas: Wipe the sheet pan if needed.
Lightly brush or spray it with oil. Lay 4 tortillas across the pan. Sprinkle each with a layer of cheese.
Spoon the veggie-bean mixture evenly over the cheese, leaving a small border. Top with remaining cheese, then place the other 4 tortillas on top.
Brush for crispness: Lightly brush the tops with the remaining tablespoon of olive oil. This helps them brown and crisp in the oven.
Bake to golden: Bake for 10–12 minutes, flipping halfway if you want even color on both sides.
They’re done when the tortillas are golden and the cheese is melted and gooey.
Slice and serve: Let rest for 2–3 minutes, then cut into wedges with a sharp knife or pizza cutter. Serve with salsa, sour cream or Greek yogurt, hot sauce, and lime wedges.