Peel the squash, cut it into 1/2-inch cubes, and put them in a large pot. Add the butter, 1 1/2 cups of water, and 3/4 teaspoon of kosher salt. Bring to a simmer over medium-high heat. Turn the heat to medium-low, cover the pan, and cook for 30 to 45 minutes or until the squash is tender. Check occasionally and add more water if necessary. Add the brown sugar (if using) and cook for a few more minutes or until the sugar has dissolved.

Mash the squash until it is smooth, adding salt and pepper as needed to taste. If the mash is very thick, add some water, broth, or milk to loosen it up.

Enjoy!