Step 1

In a large pot or Dutch oven over medium heat, melt the butter. Add the onions and salt, stir, cover and cook for 5 minutes. Uncover and cook, stirring occasionally, until the onions are nicely browned in spots and the bottom of the pot is covered with stuck-on bits, 20 to 25 minutes.

Step 2

Add the port to deglaze by scraping up any browned bits stuck to the bottom of the pot.

Step 3

Add the stock or broth, pasta, thyme, and pepper, cover partially and increase the heat to bring to a boil. Cook, stirring occasionally and adjusting the heat as needed to keep the mixture at a gentle, not rolling, boil, until the pasta is al dente and the liquid has reduced to coat the pasta, 15 to 20 minutes (see NOTE). Remove from the heat, discard the thyme, and stir in the cheese until melted. Taste, and season with more salt and/or pepper, if needed.

Step 4

Divide among bowls, sprinkle with more cheese and fresh thyme leaves, if desired, and serve.

Step 5

NOTE: The pasta will continue to absorb liquid as it sits, so it’s okay if it is still saucy.

Step 6

CORRECTION: In an earlier version of this recipe, the nutritional analysis included an incorrect amount for the total fat.