Prepare ingredients: grate the cheese if needed, slice the tomato, finely slice the red onion, and finely chop the chilli. Shred or slice the cooked chicken if not already prepared.
Heat a large dry frying pan over medium-low heat.
Place one tortilla in the pan and spread one-quarter of the grated cheese over one half of the tortilla.
Top the cheese with half of the cooked chicken, then sprinkle about ½–1 teaspoon of Cajun seasoning over the chicken as desired.
Add half the sliced tomato, scatter some sliced red onion, sprinkle half of the chopped chilli, and top with a small handful of spinach leaves.
Sprinkle another quarter of the cheese over the fillings, fold the tortilla over or place a second tortilla on top to make a sandwich.
Cook for about 3 minutes until the bottom is golden and the cheese begins to melt, then carefully flip using a spatula and cook a further 3–4 minutes until golden and the cheese is fully melted.
Remove from the pan, slice into wedges, and repeat the process with the remaining tortillas and fillings to make the remaining quesadillas.
Serve the quesadillas hot with lime wedges for squeezing over.
