In a large non-reactive bowl, combine the meat, wine, vinegar, 3/4 cup onions, 1/2 cup carrots, 1/2 cup celery, garlic, rosemary, thyme, cloves, parsley stems, bay leaves, juniper and peppercorns. Stir to combine, cover, and marinate 24 to 36 hours, refrigerated.

Drain the meat thoroughly, reserving the liquid, and pat dry.

In a large pot, cook the pancetta over medium heat until brown and the fat is rendered. Remove and drain on paper towels. In batches, add the drained meat and cook, stirring, until browned on all sides, about 10 minutes. Remove from the pan. Add the remaining onions, carrots, and celery, and the minced garlic. Cook, stirring, until soft. Add 1 cup of the reserved marinade and bring to a boil, stirring to deglaze the pan. Return the meat and pancetta to the pan and add enough marinade to come halfway up the sides of the meat. Reduce the heat, cover slightly, and simmer until the venison is tender, stirring occasionally, about 1 1/2 hours. (The cooking liquid should reduce and thicken as the meat cooks, yet add additional liquid should be added as needed to keep the meat halfway covered during cooking.)

In a large skillet, melt 2 tablespoons of the butter in a large skillet. Add the mushrooms and cook until tender and starting to brown. Remove from the heat and reserve.

Bring a large pot of salted water to a boil. Add the egg noodles and cook until al dente. Drain well and return to the pot. Toss with the remaining 2 tablespoons of butter and cover to keep warm until ready to serve.

To serve, place the egg noodles in a large serving bowl. Top with the stew and arrange the cooked mushrooms over the stew. Garnish with fresh parsley and serve.