Bake pie crust as directed on packaging. Meanwhile brown beef over medium heat until there is no pink. Add onion and garlic if desired. Add 1/2 jar of Ragu spaghetti sauce and allow to simmer.
Boil peeled potatoes until soft. Add 1/2 stick butter and mash potatoes. Add enough milk to make the potatoes creamy.
Add sauce mixture to fill the pie crust. Spread mashed potatoes across the top of the ground beef. Sprinkle cheddar cheese over potatoes if desired.