Preheat oven to 375*F.
Cut the loaf of bread in half lengthwise and scoop out the soft inner portion of each half, leaving at least 3/4" of crust all the way around. Do not leave the crust too thin or it will tear.
In a large saute pan, heat 2 tbls. of the olive oil over medium high heat. Add the onions and saute until translucent, about 3-4 minutes. Add the garlic and tomatoes and cook for about 3-4 more minutes. Remove from heat and set aside to cool.
In a large bowl, toss the diced lamb, red pepper flakes, oregano, parsley, salt and pepper. Add the tomato mixture and continue tossing until blended.
Brush the inside of the hollowed out bread loaf with the remaining 4 tbls. olive oil and sprinkle in the grated cheese. Fill the bottom half of the bread cavity with the meat mixture and carefully place the top half over it, securing it tightly. Wrap tightly with heavy duty aluminum foil(or double wrap with regualr foil), leaving one seam along the top so you can check to see when the meat is cooked. Place the foil wrapped loaf on a baking sheet and bake for 1 1/2 hours. Unwrap the foil at the top seam and check to see if the meat is done. (Till just slightly pink, or cook till it's done the way you like it). If the filling isn't piping hot all the way through, rewrap the sandwich in foil and bake for another 20-30 minutes.
When done, let the sandwich cool slightly before cutting. Slice and serve warm, or wrap in another layer of foil and pack the sandwich in a picnic basket. Enjoy!