Chicken Quesadillas

4 8-inch flour tortillas
2 t melted butter
1 cup shredded cheddar cheese
1/3 cup finely chopped onion
1 medium chopped tomato
1 cup chopped, cooked chicken

Brush one side of each tortilla with butter.  Place 2 of them, buttered side down, on hot griddle.  Sprinkle with cheese, onion, tomato, and chicken.  Top with remaining tortillas, buttered side up.  Cook over medium heat 3-4 minutes per side.  Cut into wedges and serve.