01 - Preheat a large skillet or griddle over medium heat.
02 - Lay a tortilla flat on a clean surface. Sprinkle 1/2 cup Monterey Jack and 1/4 cup cheddar cheese evenly over half of the tortilla.
03 - Distribute 1/4 cup jalapeños, 1/4 cup pickles, and sliced red onion over the cheese. Incorporate fresh cilantro, if using.
04 - Fold the tortilla in half to enclose the fillings, creating a semicircle.
05 - Lightly spread softened butter on the outside of the folded tortilla.
06 - Place the prepared quesadilla onto the preheated skillet. Cook for 2 to 3 minutes per side, applying gentle pressure, until the exterior is golden brown and the cheese is thoroughly melted.
07 - Remove the cooked quesadilla from the skillet. Allow it to rest for 1 minute before slicing into wedges.
08 - Repeat the assembly and cooking steps for the remaining tortillas and fillings.
09 - Serve the quesadilla wedges hot, accompanied by sour cream and salsa or hot sauce.