Bring a pot of water to boil over high heat. Add the gnocchi and cook according to package directions.
Add 2 tablespoon butter to a large skillet over medium heat.
Once melted, add the mushrooms and cook until they are softened and lightly browned. You might want to do this in two batches, as mushrooms like a lot of space when they are cooking. This takes about 8-10 minutes. Remove from the skillet and set aside.
If needed, add another tablespoon of butter. Add the shallots and cook until slightly softened, about 5 minutes.
Add the garlic and rosemary, and cook another minute.
Slowly add the chicken broth, whisking to combine and to loosen up anything on the pan.
Whisk in the dijon mustard, cream, and Parmesan cheese and bring to a light simmer for about 5 minutes. The sauce should thicken up a bit. Season with salt and pepper, to your preferred taste.
Add the cooked gnocchi and mushrooms and mix well.
Serve topped with additional fresh rosemary.
Enjoy!