Heat a medium pot over medium heat. When hot, add the oil.
1 Tablespoon vegetable oil
Add the mushrooms and cook until lightly browned, approximately 3 minutes.
6 ounces mushrooms
Add the garlic, rosemary, and cornstarch. Stir to combine. Cook until fragrant and flour is cooked, 1 minute.
½ Tablespoon minced garlic ½, 1 Tablespoon cornstarch, ½ Tablespoon dried rosemary
Add the wine, stock, salt, and pepper. Simmer for 10 minutes.
1 ½ cups vegetable stock, 1 ½ cups marsala wine, ½ teaspoon salt, ¼ teaspoon black pepper
Add the butter and stir in to combine into the sauce. Remove from heat.
2 Tablespoons butter
Toss with pasta or use as desired. Add more stock, pasta water, or water as needed to loosen and get the consistency you want. Or thicken with more cornstarch mixed into liquid over a simmer.
Notes
This is enough to mix with one pound of pasta.Easily skip the cornstarch/flour which will result in a thinner broth-like sauce.Gluten free when using cornstarch and not flour.