Bennigan's Baked Potato Soup

3 lbs all purpose potatoes, scrubbed and pierced in several places
1 tbsp stick butter or margarine
1 1/2 cups finely chopped onions
2 tbsp minced garlic
1 {14 1/2 oz} can chicken broth
3 cups milk
1 tsp salt
1/2 tsp pepper

toppings:
shredded cheddar cheese
crumbled bacon
chopped scallions

preheat over to 400
bake potatoes 1 hour or until tender, peel potatoes when cool to touch
melt butter in a 6 qt pot over medium low heat
stir in onions and garlic
cover and cook 10 minutes until soft, but not brown
add 2/3 of the potatoes and mash with a potato masher
add broth, milk, salt and pepper
bring to a simmer, stirring occasionally
cut remaining potatoes in small cubes and add to soup
stir gently to a simmer
simmer on low, stirring occasionally, for at least 30 minutes, allowing soup to thicken
serve and sprinkle with desired toppings