Prepare mango salsa in a medium bowl and set aside.
Quesadilla fillings: Mix up the seasoning in a small bowl and set aside.
In a large pan, heat olive oil over medium heat. Add the bell peppers and onion to the pan and cook until softened, 5 or so minutes.
While the veggies are cooking, prepare the shrimp (remove tails, devein etc). Toss in half of the seasoning mix.
Add the shrimp to the pan and sprinkle with remaining seasoning. Toss to coat all veggies and shrimp evenly. Cook for another 3-5 minutes, or until shrimp are pink and cooked through.
Squeeze the lime juice over the filling.
Transfer shrimp/veggies to a plate, rinse the pan, spray with spray oil and return to the burner.
Assemble the quesadillas: Add a large tortilla to the pan, then sprinkle with ¼ cup of cheese. Add ¼ of the shrimp/veggie filling, then add another ¼ cup of cheese on top. Fold the quesadilla over and weigh down with a pot lid or heavy plate.
Cook for around 2 minutes, until golden brown, then flip. Cook for another minute before setting aside.
Repeat with the other 3 tortillas.
For a kid-friendly version, leave the cayenne out! For a mild spice, add ½ teaspoon cayenne. For a spicier quesadilla, add more!