In a large saucepan over medium-high heat, melt butter and add onions; saut in the butter until the onions are translucent; add the garlic and stir a couple of times, then immediately stir in the chicken broth.
Add potatoes, (add water if needed to barely cover potatoes) bring to a boil and reduce to a medium boil and cook until potatoes are tender (about 20-25 minutes).
Add the half and half and bring to a low boil and continue cooking for an additional 10 minutes, stirring occasionally. Season with salt and pepper to taste.
For a smoother soup, you may blend with a stick blender or mash with the back of a spoon while stirring.