12 ounces wide egg noodles
2 tablespoons unsalted butter (1/4 stick)
24 ounces fresh Bockwurst Sausage (about 6 sausages)
2 cups peeled, medium-dice celery root, also known as celeriac
2 cups medium-dice yellow onion
16 ounces white mushrooms, stemmed and quartered
1 cup dry Riesling or a sweet white wine
2 tablespoons all-purpose flour
2 cups low-sodium chicken broth
4 teaspoons Dijon mustard
1 cup heavy cream