Place potatoes into a large pot of cold salted water. Bring to a boil over medium-high heat. Once water is boiling, cook for 10-12 minutes or until potatoes are fork tender. Drain and transfer to a large mixing bowl.
With an electric mixer, beat on low until potatoes are mashed, then add butter, Parmesan cheese, garlic, milk, salt and pepper to taste. For thinner mashed potatoes slowly add more milk, until desired consistency.
Alternative Method: Mash the potatoes by running them through a ricer OR food mill to make them extra fluffy, then fold in remaining ingredients.
Roasted Garlic: Preheat oven to 350 degrees. Slice the top off of a garlic bulb, drizzle with olive oil. Wrap tightly in foil and bake for 1 hour. Note: One garlic bulb will yield around 12 cloves.