Preheat oven to 400F. Trim about 1/2-inch off the top of the head of garlic, exposing all the cloves inside and drizzle with olive oil. Wrap the heads in foil and bake for 40-45 minutes, or until cloves are soft. When done, remove foil and set aside to cool. When cool enough to handle simply put some pressure on the cloves and they will slide out.

Heat a 2­-quart pot over medium heat and add the butter (or ghee) and olive oil to the pot and stir until melted. Add the sliced leeks and potatoes and cook, stirring occasionally, until the vegetables have begun to soften and brown slightly, about 6-8 minutes.

Add the chicken stock, white wine, diced garlic, thyme, and a generous pinch of salt and pepper. Stir to combine, scraping up any stuck bits from the bottom of the pan. Bring mixture to a boil, and then turn heat down to a bubbling simmer. Cook until potatoes are tender, about 20-25 minutes.

When the potatoes are tender, remove a couple of cups of the potatoes (see notes) and puree the remainder of the soup using an immersion blender or a regular blender (in batches) and return it back to the pot. Add the bacon, sour cream, and half and half and season with salt and black pepper. Warm on medium heat for five minutes and serve garnished with a drizzle of olive oil and chopped parsley.