In a small skillet, saute in butter.
In a small bowl, beat together eggs and seasoning salt. When vegetable are tender, pour eggs over and scramble the mixture until soft curds form.
Place one tortilla in quesadilla maker (or large frying pan on medium high heat). Evenly spread with egg mixture starting from the centre, making sure to leave edges clear for sealing. Sprinkle cheese on top. Cover with second tortilla and close quesadilla maker lid. Cook for 3 to 4 minutes until golden brown. If using a frying pan, cover for 2 to 3 minutes, or until quesadilla is set, then flip over and cook for another 1 to 2 minutes.
Remove from quesadilla maker. Let cool slightly and serve.