Preheat oven to 400 degrees F. Cut bread in half lengthwise and scoop out a cavity in both halves, being careful not to rip bread or leave too thin a crust
. It should be 3/4-inch thick. On medium heat, in 2 tablespoons olive oil, saute the onions until translucent, add in the garlic and tomato. Cook for 3 to 4 minutes and set aside and let cool. In a bowl, toss together the lamb
, chili flake, oregano, salt and pepper. Add in the onions
, garlic, and tomatoes. Blend
well. Brush insides of the bread with remaining 4 tablespoons olive oil and sprinkle with grated cheese
. Fill bottom half of bread cavity with the meat and carefully place top half over it, securing tightly. Wrap with aluminum foil and bake for 1 1/2 to 2 hours. Slice crosswise and serve warm.