Soften the cream cheese ahead of time by leaving it on the counter 20–30 minutes, or microwave in 5-second bursts until slightly yielding.

Heat a large deep skillet or wide pot over medium heat. Add butter and olive oil until shimmering.

Add the chopped onion; cook 4–5 minutes until translucent.

Add sliced mushrooms and 1 teaspoon salt. Sauté 6–8 minutes, stirring occasionally, until mushrooms release their liquid and start to brown.

Stir in minced garlic, 1 teaspoon dried thyme, 1/2 teaspoon dried parsley (if using), and 1/2 teaspoon black pepper. Cook 30–60 seconds until fragrant.

Pour in 3 cups low-sodium broth and bring to a simmer. Scrape any browned bits from the pan for flavor.

Add 8 ounces uncooked short pasta to the simmering broth. Reduce heat to medium-low and cook uncovered, stirring occasionally, until pasta is al dente and most broth is absorbed — about 10–12 minutes (check package directions).

Lower the heat. Stir in 1 cup heavy cream, the softened 4 ounces cream cheese (add in cubes; stir until melted), and 1/2 cup grated Parmesan. Cook 2–4 minutes, stirring, until sauce is smooth and heated through.

If you want a thicker sauce, mix 1 tablespoon cornstarch with 2 tablespoons cold water in a small bowl, then stir the slurry into the pot and simmer 1–2 minutes until thickened.

Taste and adjust salt and pepper.

Serve hot, garnished with chopped fresh parsley and an extra sprinkle of Parmesan if desired.