1Heat oven to 400^. Generously grease a 9x13-inch baking pan. Combine enchilada sauce and sour cream in a medium bowl. Combine chicken, onion and garlic in a large skillet and sauté until onion is tender; Stir in oregano leaves and chilies. Sprinkle crushed tortilla chips evenly in prepared pan Spread with 1/3 of the enchilada mixture. Top with 1 cup of the cheddar cheese; spread with 1/2 the chicken mixture. Repeat with chicken, sauce, and cheese.
Beat milk, eggs and Bisquick until smooth, 15 seconds in blender on high; or 1 minute with hand beater. Pour into pan over cheese. Bake until knife inserted in center comes out clean, 25 to 30 minutes. Sprinkle with a little more cheese and bake 3-5 minutes, until cheese is melted. Cool at least 10-15 minutes, before serving.
Serve with chopped tomato, shredded lettuce and dairy sour cream and black olives.