Slow Cooker Potato Soup

LBA (and Mrs. BA) really love the Baked Potato Soup.  I bet this would make everyone feel good.
From Gimme Some Oven via BuzzFeed.

Slow Cooker Potato Soup
Yield: 8-10 servings
Prep Time: 10 mins 
Cook Time: 4 hours 10 mins 
Total Time: 4 hours 20 mins 

Ingredients

• 6 slices cooked bacon*, diced
• 3-4 cups good-quality chicken or vegetable stock 
• 2 pounds Yukon gold potatoes**, peeled (if desired) and diced 
• 1 medium white or yellow onion, peeled and diced 
• 4 tablespoons bacon grease* (or butter) 
• 1/3 cup all-purpose flour
• 1 (12-ounce) can 2% evaporated milk 
• 1 cup shredded reduced-fat sharp cheddar cheese 
• 1/2 cup plain low-fat Greek yogurt or low-fat sour cream 
• 1 teaspoon Kosher salt, or more to taste 
• 1/2 teaspoon freshly-cracked black pepper 
• optional toppings: thinly-sliced green onions or chives, extra shredded cheese, extra bacon, sour cream 

Directions

1. Add bacon, 3 cups chicken stock, potatoes and onion to the bowl of a large slow cooker, and stir to combine. Cook on low for 6-8 hours or on high for 3-4 hours, or until the potatoes are completely tender and cooked through. 
2. Once the soup has slow cooked and is about ready to serve, cook the butter in a small saucepan on the stove over medium-high heat until it has melted. Whisk in the flour until it is completely combined, and then cook for 1 minute, stirring occasionally. Gradually add in the evaporated milk while whisking it together with the flour mixture, and continue whisking until the mixture is completely smooth. Let the mixture continue cooking until it reaches a simmer, stirring occasionally, and then it should get really thick. 
3. Immediately pour the milk mixture into the slow cooker with the potatoes, and stir until combined. Add in the cheddar cheese, Greek yogurt (or sour cream), salt and pepper, and stir until combined. If you would like the soup to be even thicker, you can use a potato masher or a large spoon to mash about half of the potatoes (while the soup is still in the slow cooker) to thicken the soup up. If you would like the soup to be thinner, add in an extra 1-2 cups of warmed chicken or vegetable stock. Stir to combine, then taste and add more salt and pepper if needed. 
4. Serve warm, garnished with desired toppings. Or transfer to a sealed container and refrigerate for up to 3 days. (This recipe will not freeze well.) 

*You can either fry the bacon, cook it in the microwave, or buy pre-cooked bacon. If frying or microwaving, I recommend dicing the bacon before cooking it. And if you are frying it, I highly recommend saving the bacon grease for later and then using it to make your roux (instead of butter).

**I highly recommend using Yukon gold potatoes, which have the perfect texture and buttery taste for this soup. But Russet potatoes or red potatoes would also work just fine in this recipe.

***If you would like to make this recipe vegetarian, use vegetable stock, omit the bacon, and I would recommend adding in 2-3 teaspoons of Old Bay seasoning for extra flavor.