Mix cheese, ham, olives, and onions in a small bowl.
Spread 1 tablespoon of mustard on each tortilla shell and spread about 1/3 cup of the gouda mixture over 1/2 of the tortilla. Fold the tortilla in half to cover the filling. Heat the filled tortillas in a large nonstick skillet over medium heat for 4 minutes or until cheese melts, turning once half way through cooking.
Cut the quesadillas into 3 wedges and place on serving platter. Garnish with sour cream and peppers.