Prepare spaetzle following package directions. Drain.
Meanwhile, in a large bowl, mix together the veal, bread crumbs, eggs, onion flakes, thyme, salt and pepper. Form into 24 meatballs, about 2 tablespoons each. Coat a 13 x 9-inch baking dish with nonstick cooking spray. Add meatballs to dish and cover with plastic wrap. Microwave, covered, on high 5 minutes.
Melt butter in a large nonstick skillet. Add the flour and cook 1 minute. Whisk in broth and simmer 1 minute. Add meatballs and mushrooms. Cover and simmer 8 minutes, stirring halfway through cooking.
Over low heat, stir in the sour cream, mustard and parsley. Heat through. Serve the meatballs over the cooked spaetzle. Makes 6 servings.