Bring a large pot of salted water to a boil. Add the 8 oz of pappardelle pasta and cook according to the package instructions until al dente, usually about 7-9 minutes. Reserve 1/2 cup of the pasta water before draining the pasta in a colander. Set the pasta aside.
While the pasta cooks, heat 1 tablespoon of olive oil and 1 tablespoon of butter in a large skillet over medium-high heat. Once the butter has melted and is bubbling, add the sliced cremini mushrooms. Sauté for about 5-7 minutes, stirring occasionally, until the mushrooms release their moisture and turn golden brown.
Reduce the heat to medium and add the minced garlic and 1 teaspoon fresh thyme to the skillet with the mushrooms. Cook for another 1-2 minutes until the garlic is fragrant but not burned.
Pour in 1 cup of heavy cream, stirring to combine with the mushrooms. Let the mixture simmer gently for 3-4 minutes until the cream thickens slightly. Season with salt and pepper to taste. If the sauce seems too thick, add a splash of the reserved pasta water to loosen it up.
Add the drained pappardelle to the skillet and toss gently to coat every ribbon in the creamy mushroom thyme sauce. Stir in 1/2 cup grated Parmesan cheese until melted and smooth. If needed, add more pasta water to reach your desired consistency.
Transfer the pasta to serving plates or a large bowl. Sprinkle with chopped parsley for a fresh pop of color and serve immediately.
