Preheat oven to 350ºF. Grease a 7” x 10” baking pan.
Place frozen veggie in a microwave-safe dish with 1/2-inch of water. Microwave, covered, on high for 2 minutes.
Distribute semi-frozen veggies (chop a bit if pieces are too large) and onions in the bottom of prepared pan.
In another bowl beat eggs, milk, mayo, sour cream, cheese and spices until smooth. Pour over vegetables.
Mix topping ingredients and sprinkle over top. Bake for 35-40 minutes.