Prepare the Potatoes:

Peel and dice the potatoes into bite-sized pieces.

Cook the Aromatics:

In a large pot or Dutch oven, melt the butter over medium heat. Add the chopped onion and garlic, sautéing until soft and fragrant.

Make the Roux:

Sprinkle the flour over the onions and garlic, stirring continuously to create a roux. Cook for 1–2 minutes to remove the raw flour taste.

Add Broth:

Slowly whisk in the chicken or vegetable broth, ensuring there are no lumps.

Cook the Potatoes:

Add the diced potatoes and dried thyme. Bring the mixture to a boil, then reduce the heat and simmer until the potatoes are tender (about 15–20 minutes).

Blend for Creaminess:

For a smooth soup, use an immersion blender to blend until creamy. Alternatively, remove half of the soup, blend it in a blender, and return it to the pot. For a chunkier soup, leave the potatoes as is.

Add Cream:

Stir in the milk or heavy cream, letting it heat through without boiling.

Season to Taste:

Add salt and pepper to taste. If using cheese, stir it in until melted and fully incorporated.

Serve:

Ladle the soup into bowls and garnish with chopped parsley or chives.