Roughly peel potatoes, leaving a little bit of skin on if desired, and dice into cubes.
Add the cubed potatoes into a pot of cold water, bring to a boil and cook for 8 minutes.
Remove and drain the potatoes into a colander set into a sink. Let the potatoes cool. Set aside.
In a 10-inch skillet melt three tablespoons of butter over medium-low heat.
Add in the diced onions. Cook until just softened
Add in the minced garlic. Cook for one minute.
Sprinkle in the flour and stir, cooking for 2-3 minutes.
While stirring, pour in broth and milk. Continue to stir until thick, about 5-8 minutes.
Remove the pan from the heat and stir in the cup of cold sour cream.
In a large bowl add in the cooled potatoes, onion and sour cream mixture, green onions, salt, pepper and shredded cheese. Stir to combine and pour into greased pan. Bake in a 350 degree oven for 1 hour or until bubbly and lightly golden. Enjoy!