Use a sharp knife to slice the top off the head of garlic, just to expose the top of each clove and leaving most of the skin on. In a small baking dish lined with foil, place the head of garlic in the center of the foil. Drizzle with olive oil and sprinkle with kosher salt. Wrap up the garlic with the foil and roast in the oven for 30 minutes until the garlic is golden brown. Set the garlic aside to cool before squishing the garlic from the skin.
In a large pot, over medium heat fry the bacon, flipping frequently until crispy. Set the bacon aside to cool. Crumble once cooled.
Add the butter and shallots to the pot and saute just until fragrant. Add the beans, sage and chicken broth and bring to a boil. Reduce the heat to medium-low and simmer for about 15 minutes.
Remove the sage and add the roasted garlic to the pot. Blend the soup with an immersion blender until completely smooth (or your desired consistency) or blend in batches using a countertop blender.
Divide the soup into containers, and top each serving with crumbled bacon. Allow to cool and store in the fridge or freezer.