Peel and cut potatoes into 8 sections.
Add water to completely cover potatoes. Cook until fork tender then drain out water.
Place potatoes in large mixing bowl. Add sour cream, butter and milk and beat until creamy and smooth.
Add spinach, garlic salt, salt, pepper. and Parmesan and beat until well mixed in.
Stir in 1 cup cheddar cheese and garnish the top with additional ¼ cup cheddar cheese.
