Heat milk in microwave for three minutes (this reduces whisking time once you add it to the soup pot)
Melt butter over medium heat in large pot. Add the flour and whisk until smooth. Gradually stir in milk, whisking constantly until thickened. I also add in 2 whole slices of bacon and 2 whole green onions during this process to add flavor without chunks of things my kids won't eat.
Once thickened, remove optional bacon slices and green onion. Add chopped potatoes and bring to a boil, stirring frequently.
Reduce heat to low and simmer for 10 minutes. During the simmer, if you want the soup to be a little thicker, remove a scoop of potatoes with a slotted spoon, mash them with a fork and stir back in to the soup. Alternatively, if you want the soup to be thinner, add chicken broth or more milk.
Mix in cheddar, salt, pepper and sour cream (to prevent sour cream from curdling, add some soup to sour cream in a separate bowl to temper it before adding it to the pot.)
Serve with toppings of your choice. Enjoy!