From Mr. Food. Easy Cheesy Cottage Pie requires just a few ingredients and you can have it on the table in less than 30 minutes. Seriously! It doesn't get much better than a hearty dinner you can make in a snap.
Preheat oven to 400 degrees F. Coat a 2-quart casserole dish with cooking spray. In a large skillet,melt butter. Add onion and cook until lightly browned,stirring frequently. Stir in beef,salt and pepper and cook 5-8 minutes or until beef is no longer pink.
Stir in gravy and heat until bubbling. Spoon mixture into prepared casserole dish. In a small bowl,combine potatoes and cheese. Spread over top of casserole. Bake 15 to 20 minutes,or until potatoes are lightly browned and casserole is warmed through.