Classic Old-Fashioned Stewed Potatoes

Sauté the Base In a large pot or Dutch oven, melt 2 tablespoons of butter. Add the onion (and bacon, if using) and sauté over medium heat until the onions are soft and translucent (about 5 minutes).
Add the Potatoes Add your cubed potatoes to the pot. Pour in just enough water to barely cover the tops of the potatoes. Add a heavy pinch of salt and a teaspoon of black pepper.
The Simmer Bring the water to a boil, then reduce the heat to medium-low. Cover and simmer for about 15–20 minutes.

The Trick: You want the potatoes to be fork-tender, with some of the edges starting to round off and “melt” into the water.
The “Creaming” Phase Once the potatoes are tender, do not drain the water! Turn the heat to low. Add the remaining 2 tablespoons of butter and the milk.
The Mash & Thicken Use a wooden spoon to gently smash a few (just 4 or 5) of the potato chunks against the side of the pot. Stir them back in. The starch from the smashed potatoes will mix with the milk and butter to create a thick, creamy sauce.
The Final Season Let it simmer uncovered for another 5 minutes until it reaches your desired thickness. Taste and add more salt or pepper as needed.

The Russet Choice: Always use Russet potatoes for stewing. Waxy potatoes (like Red Bliss or Yukon Gold) hold their shape too well; you want a starchy potato that is willing to fall apart a little to create that “gravy.”
Don’t Over-Water: If you drown the potatoes in too much water, the starch will be too diluted, and you’ll end up with potato soup instead of stewed potatoes.
The “Peppery” Profile: Traditionally, this dish is quite peppery. The bite of the black pepper cuts through the creaminess of the butter and milk perfectly.