Cheesy Baked Potato Soup

Step 1

Set the oven to 375°F and wait until the indicator light or beep tells you it has finished heating, about 10 minutes.

Step 2

Wash the potatoes under cold running water, rub them dry with a clean cloth, and poke each one 5 times with a fork to let steam escape.

Step 3

Place the potatoes directly on the oven rack in the center of the hot oven, with a baking sheet on the rack below to catch drips.

Step 4

Bake the potatoes until a fork pierces the largest one with no resistance, about 30 minutes.

Step 5

While the potatoes bake, place the onion on a cutting board and cut in half lengthwise from root to tip, then lay each half flat and slice crosswise into thin half-moon pieces, about 1/4-inch thick.

Step 6

Melt 4 tablespoons of butter in a large heavy-bottomed pot over medium heat, stirring occasionally until the butter bubbles slightly and foams, about 2 minutes.

Step 7

Add the sliced onion to the melted butter and stir with a wooden spoon, scraping the bottom of the pot once every 30 seconds until the onion turns soft and golden, about 6 minutes.

Step 8

Sprinkle the flour over the onion and stir constantly with the wooden spoon for 90 seconds until the mixture looks like wet sand.

Step 9

Remove the pot from the heat and pour in the milk slowly while stirring continuously to break up any lumps, until the milk is fully mixed in and smooth.

Step 10

Return the pot to medium heat and stir the milk mixture once every 30 seconds until it thickens enough to coat the back of a spoon and steam rises gently, about 8 minutes.

Step 11

Remove the pot from the heat and stir in the shredded cheese using a wooden spoon until every piece has melted and the mixture looks smooth and glossy, about 2 minutes.

Step 12

Season the cheese sauce with salt and pepper: add a small pinch of each, stir, taste with a spoon, and repeat until it tastes good to you.

Step 13

Remove the hot potatoes from the oven using oven mitts and place them on a cutting board until cool enough to touch, about 5 minutes.

Step 14

Cut each potato in half lengthwise, and use a spoon to scoop out the soft inside into the pot with the cheese sauce, leaving a thin shell of potato skin in each halved potato skin.

Step 15

Stir the mixture in the pot gently with a wooden spoon for 30 seconds until the potato pieces are distributed evenly throughout the cheese sauce.

Step 16

Pour the creamy potato mixture from the pot into a 9-by-13-inch baking dish, spreading it evenly across the bottom with the spoon.

Step 17

Place the baking dish uncovered in the oven and bake until the top looks golden brown with small bubbles around the edges, about 8 minutes.

Step 18

Remove the baking dish from the oven using oven mitts and let it rest at room temperature for 3 minutes before serving, so the soup stays thick.

Step 19

Ladle the soup into bowls and scatter fresh chopped chives or a dollop of sour cream on top of each bowl, if desired.