Heat a large skillet or griddle over medium. If using a press, preheat it. Mix your spices with a pinch of salt and pepper in a small bowl.
If using tomato or pico, blot with a paper towel to avoid soggy tortillas. Water is the enemy of crisp.
In a bowl, toss bell pepper, onion, spinach, jalapeño, corn, tomato, cilantro, and the spice mix. Taste and adjust salt.
Lay a tortilla on a board. Sprinkle about 1/4 cup cheese over half the tortilla.
Add a thin, even layer (roughly 1/3 cup) of the seasoned veggies over the cheese. Don't pile high—thin layers melt and seal better.
Top with another 1/4 cup cheese. Fold the tortilla over to form a half-moon, pressing gently.
Add a light swipe of butter or oil to the hot pan. Place the folded quesadilla in and cook 2–3 minutes until the bottom is golden and the cheese starts melting.
Carefully flip with a spatula. Cook another 2–3 minutes until deeply golden and crisp. If needed, lower heat to prevent scorching while the cheese melts.
Transfer to a wire rack (not a plate, so the bottom stays crisp). Repeat with remaining tortillas, adding a touch more butter or oil as needed.
Rest 1 minute, then cut into wedges. Serve with salsa, guac, yogurt/sour cream, and a squeeze of lime.