Heat a large skillet over medium heat and melt 1 tablespoon butter.
Place a tortilla in the skillet over the melted butter. Sprinkle 1/2 cup cheese on one half of the tortilla and spread 1 tablespoon salsa on the opposite side.
Allow the cheese to melt for approximately 2 minutes, then fold the tortilla in half.
Continue cooking for an additional minute, then flip the quesadilla to brown the other side and ensure the cheese melts thoroughly.
Repeat the process for the remaining tortillas and ingredients, adding butter to the skillet as necessary.
Once cooked, remove the quesadilla from the skillet and slice into wedges.
Serve with guacamole, sour cream, and additional salsa on the side.