Saute onions over medium heat until soft and translucent

Add garlic, and saute another 30 seconds

Add broth, potatoes and squash. Bring to a boil, and reduce to simmer for 30 minutes until vegetables are tender.

Remove from heat, and puree until smooth (I use my hand-held emulsion blender for this)

Stir in milk, return soup to stove-top, and heat through

Garnish with croutons, parsley or sour cream if you wish