Bring potatoes and turnips to a boil over medium-high heat for about 25 minutes, until tender.

Once boiled, add potatoes and turnips to a large mixing boil and mash.

Add hot milk and sour cream.

Whip until mixture is light and fluffy.

In a hot nonstick skillet, sauté onions till they are light brown, about 2 to 3 minutes. Add garlic. Cook over medium heat for 10 minutes.

Fold caramelized onions into potatoes and turnips.