Peel potatoes.

Boil potatoes until soft. Approximately 30 minutes.

Drain potatoes then place in large mixing bowl.

Add the salted butter to the potatoes while they are still warm and mash them together.

Add milk, egg and garlic powder to the potatoes and mash then together. Set aside.

Grate the onion.

Sauté grated onion in melted butter until the onion is soft but not brown.

Add onion to potato mixture. Mash together.

Preheat oven to 350°F.

Mash cheddar cheese into the potatoes.

Spread potatoes in greased 9x11 baking pan.

Bake at 350°F until edges are golden brown (approximately 30 minutes).