Preheat your oven to 450 degrees. Scatter the cauliflower on a rimmed sheet pan and toss with a tablespoon of olive oil, a couple pinches of salt and a 1/4 teaspoon of black pepper. Roast for 20-30 minutes. Let cool and toss in a blender with the milk. Remove the center piece to the lid to your blender, cover the hole with a kitchen towel and puree until smooth. Pour the cauliflower puree into a giant bowl.

Meanwhile in a large Dutch oven, sauté the onion, garlic, thyme in a half tablespoon or so of olive oil until soft. Throw in the diced potatoes, bay leaf, 1/2 teaspoon of kosher salt and chicken stock, cover and bring to a boil. Reduce the heat and simmer for 20-30 minutes {depending on the size of the potatoes}.

Once the potatoes are cooked through, ladle half of the potato mixture into the blender and pulse until coarsely chopped. Pour into the bowl with the cauliflower puree and repeat with the remaining potatoes.

Pour the potato/cauliflower mixture back into the Dutch oven and heat over medium. Taste and add another half teaspoon to a full teaspoon of salt if desired. Also season with a half teaspoon of black pepper, 1/2 cup of chopped onions and the half cup of sour cream or Greek yogurt. Stir until the sour cream has melted throughout the soup.

Ladle the soup into bowls and top them with cheddar, crispy bacon pieces and the sliced green onions.