In a skillet, cook zucchini and onion in butter until tender, about 10 minutes. Stir in parsley and seasonings. Remove from heat.
In a large bowl, blend eggs and cheese. Add zucchini mixture to the eggs and cheese and stir.
Separate crescent dough into 8 triangles, roll them thinner and place in an ungreased quiche pan or 12×8″ baking dish. Press over the bottoms and up the sides.
Spread crust with mustard. Pour zucchini mixture evenly into the crust.
Bake at 375 degrees for 18-20 minutes or until a knife comes out clean. Let stand for 10 minutes before serving. Makes 6-8 servings!