Prepare patties according to package directions; crumble and set aside.
Melt butter in a large skillet over medium-high heat; add mushrooms and onion, and sauté 5 minutes or until tender.
Process egg substitute, sour cream, and next 4 ingredients in a food processor until smooth, stopping to scrape down sides.
Stir together crumbled breakfast patties, mushroom mixture, egg substitute mixture, and Cheddar cheese. Spoon into a 10-inch quiche pan coated with cooking spray.
Bake at 350° for 35 minutes or until golden. Cool 10 minutes. Cut quiche into 8 wedges.
*If you'd rather have the meat, 1 cup lean chopped cooked ham may be substituted for vegetable breakfast patties.
Note: Individual wedges may be reheated in the microwave at MEDIUM (50% power) 1 minute or until thoroughly heated.