I remember my grandma making this and then my Papa. The entire house smelled so good we all drooled in anticipation till dinner time. I have been making mine with this same recipe for years. Today I made it and the smells take me back to my childhood. Letting it sit for a couple of hours. It always likes to sit and rest :)
Wash and layout your meat slices. Pre-fry your mushrooms in butter to golden brown. Chop your onions garlic and parsley very finely. If you have a whole pickle cut it in to half, then each half in to three pieces, length wise. Bake your bacon till golden brown in the oven on high or brown it in the broiler. It saves time while preparing all the other ingredients. Cut a slice of pumpernickle bread into long strips.
Spread a small dollop of mustard nicely all over, on each slice of beef. Put your garlic, onions and parsley in any order and spread it on each slice of meat, making sure it's all over. Put a thin slice of mozzarella cheese on each slice of meat. On the edge close to you, put a sliver of pickle, a half slice of bacon, a few golden mushrooms, a strip of pumpernickle bread. Now start wrapping/rolling it tightly and put each piece the edge down in a "clay" baking pot with a lid, (if you have one) or any baking pot big enough to fit all your bracciole. Set your oven to 300 F.
Once you have them all in, nice and snuggly, put the left over onions, garlic, parsley, and whatever is left (not the bread) on top of the bracciole. Plop a big tablespoon of real butter on top and "little" bit of olive oil. Cover and stick in the oven for 4-5 hours. Let it bake very slowly and then let it stand for at least an hour. The longer it rests the better.
Many people pound and tenderize their meat but I don't do that. It comes out juicer and very tender any way.
You may add a glass of red wine about an hour before it's done and tomato sauce 1/2 hour before it's done. I like to use the juices that come out while it's baking to make my own brown gravy. It's up to you how you like it :)
Serve with Gnocchi, or potatoes sprinkled with fresh chopped dill.