Preheat oven to 375 degrees. Boil whole potatoes until soft (but still firm); then slice into 1/4 inch slices. In a skillet, saute onion and garlic in olive oil until soft. Remove from heat and add green chilies.
In a large bowl, beat eggs; stir in veggies, seasonings and cheeses (reserve 1/4 cup of each cheese for topping).
Layer 1/2 of the potatoes in bottom of a greased 9-inch pie pan. Cover potatoes with half of the egg mixture, then add another layer of the potatoes. Top potato slices with remaining egg mixture and then remaining cheese. Bake 30-35 minutes or until set and golden brown. Serve topped with sour cream.