Sprinkle Cheddar Cheese (1 cup) over one of the Flour Tortilla (1), leaving a half-inch around the perimeter uncovered.
Sprinkle with Green Chili Pepper (1) and Onion (1 tablespoon) and top with the other Flour Tortilla (1).
Melt half the Butter (1 tablespoon) in a pan on the stove over medium-low heat. Spread around, and place quesadilla onto the pan.
Add remaining Butter (1 tablespoon) to the top of the tortilla. Let cook for several minutes over low heat. As butter softens, spread over the top tortilla. Once bottom browns and cheese is mostly melted, flip the quesadilla over.
Let cook until cheese is fully melted, and bottom is nicely browned. Remove from pan, cut, and serve with Sour Cream (to taste) and Guacamole (to taste).