In a 10" Non stick Skillet,brown up ground beef & onion until meat no longer pink;drain off fat.Stir in seasoning mix(dry)and mild chilies. Spoon into greased pie plate Heat oven to 400°F.
Stir milk, eggs and Bisquick mix until blended. Pour into pie plate. Bake about 25 minutes or until knife inserted in center comes out clean. Sprinkle with cheese. Bake 8 to 10 minutes longer. Cool 5 minutes. Serve with salsa and sour cream.