In a medium saucepan, combine broth, cream, and thyme. Bring to a gentle simmer over medium heat, stirring occasionally until thickened, about 5 to 10 minutes.

Bring a pot of salted water to a rolling boil. Add the gnocchi, cooking according to package instructions, typically 2 to 3 minutes or until they float.

Remove thyme sprigs from the sauce and stir in grated Parmesan. Continue stirring until melted. If desired, whisk cornstarch mixed with cold water before adding to sauce.

Gently fold the drained gnocchi into the creamy mushroom sauce, adding reserved pasta water if needed.

Season with salt and pepper to taste. Serve hot, garnishing with additional Parmesan and thyme.