Add potatoes and garlic to a large pot.
Add enough lightly salted water to cover.
Place pot over medium high heat and bring to a boil. Cook until potatoes are fork tender.
Remove and drain in a colander.
Add bacon to a large skillet. Place over medium heat and fry until crisp. Remove and drain on a paper towel-covered plate.
Pour out all but 1 teaspoon bacon grease from pan.
Add scallions to grease. Sauté until soft, but not brown.
Add bacon back into pan. Stir. Remove from heat.
Place drained potatoes back into pot.
Add milk, sour cream, salt and pepper. Mash potatoes to desired consistency.
Add bacon and scallions. Mix well.
Serve warm. Reheat, if necessary, before serving.