Prep the fillings: Shred the cheese. Slice or shred the turkey. If using onions or jalapeño, chop them fine so they melt into the cheese instead of falling out.
Season lightly: Toss the turkey with a pinch of salt, pepper, and the chili powder or taco seasoning if you’re using it.
This boosts flavor without overpowering the cheese.
Heat the skillet: Set a large nonstick skillet over medium heat. Add a little butter or oil and let it melt and coat the pan.
Build the quesadilla: Place a tortilla in the skillet. Sprinkle an even layer of cheese on half the tortilla, then add turkey, onion, and jalapeño if using.
Top with a bit more cheese to “glue” it shut.
Fold and cook: Fold the tortilla over to make a half-moon. Press gently with a spatula. Cook 2–3 minutes, until golden and crisp.
Flip carefully: Slide the spatula under the quesadilla and flip.
Cook another 2–3 minutes until the second side is golden and the cheese is fully melted.
Repeat: Transfer to a cutting board and make the remaining quesadillas, adding more butter or oil as needed to keep the pan lightly coated.
Rest and slice: Let each quesadilla rest for 1 minute so the cheese sets slightly. Cut into 3 or 4 triangles.
Serve: Plate with salsa, sour cream, guacamole, or a squeeze of lime. Add hot sauce if you like heat.