While noodles are cooking, in a skillet over medium-high heat, add oil and sauté mushrooms and garlic for about 6 minutes until just turning a bit brown. Add ¼ cup of beef broth and bring to a simmer. Sprinkle flour over mushrooms and toss, stirring for 1 minute. Add remaining beef broth, bring up to boil. Reduce heat and rapid-simmer for about 3-4 minutes until just starting to thicken. Stir in sour cream, Dijon, nutmeg and parsley.