In a bowl, combine the shredded cheddar cheese, Monterey Jack cheese, chopped jalapeño, chili powder, ground cumin, paprika, minced garlic, salt, black pepper, cilantro, and lime juice. Stir until everything is well mixed.

Heat a nonstick skillet or grill pan over medium heat. Add half of the butter and let it melt.

Place one flour tortilla in the skillet, spreading a quarter of your cheese mixture evenly over half of the tortilla. Fold the other half over to create a half-moon shape.

Cook for 2 to 3 minutes until the bottom is golden and crispy. Flip the quesadilla, adding the remaining butter around the edges. Cook for another 2 minutes to ensure the cheese melts and the tortilla crisps up beautifully.

Remove the quesadilla and keep it warm. Repeat with the remaining tortillas and cheese mixture.