Preheat oven to 350 F. Peel and dice potatoes into 1-inch cubes. Place potatoes into a large saucepan. Cover with water and bring to a boil. Let simmer for 15-20 minutes, until potatoes are fork tender.
Drain and place potatoes into a large bowl. Add in butter, salt, pepper and 1/2 of the french fried onions. Beat with a mixer until smooth.
Spread mashed potato mixture into a greased baking dish. Top with shredded cheddar cheese and the remaining french fried onions. Bake for 25-30 minutes.