Extra Cheesy Chile Relleno Casserole

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   ["Lightly grease an 8"" round or square pan.", "Melt butter in a medium sized skillet over medium high heat.", "Add onion, cook and stir until crisp tender.", "Stir in drained chopped chilies, then spoon mixture into prepared pan.", "Sprinkle the cheeses over the onion and chilies.", "In a small bowl, beat the eggs slightly, then beat in sour cream and pepper flakes.", "Spoon mixture evenly over the cheese mixture in pan.", "Sprinkle chopped tomato evenly over all.", "Bake at 350F for 35-45 minutes or until a knife inserted near center comes out clean."]

* Per serving · 4 servings · Values may vary.