In a small bowl, mix the Greek yogurt and chili powder. Set aside.

Heat about 25% of the oil in a large non-stick skillet over medium-high heat. Add the broccoli, season with salt and pepper, and cook until tender, about 4-6 minutes.

Sprinkle cheddar cheese on one half of the tortilla. Top with the cooked broccoli, fold the tortilla in half, and gently press to seal.

Wipe the skillet clean, then heat the remaining oil over medium heat. Add the quesadillas and cook until the cheese is melted and the tortillas are golden, about 2-3 minutes per side.

Slice the quesadillas and serve with the chili yogurt sauce.