Dice enough of the whole stewed tomatoes to make 1 cup (drained). Reserve the remaining tomatoes and juice for later.
In a large bowl, combine the ground beef, diced tomatoes, onion, bell pepper, eggs, bread crumbs, salt and pepper. Use your hands to mix the meatloaf until the ingredients are distributed evenly.
Shape HALF of the meat mixture into a loaf in a baking dish. Flatten the loaf and create an indention lengthwise down the center of the meat.
Cut the block mozzarella and fit it into the "well" created in the loaf. Take the remaining meat mixture and place it on top of the bottom half, shaping it into meatloaf form. Be sure to seal the beef around all edges so the cheese does not escape while baking.
Place the meatloaf in the oven and bake uncovered for 1 hour.
While the meatloaf is cooking, prepare the tomato sauce. In a small skillet, heat the olive oil to medium low. Add the sliced garlic and slowly simmer until the garlic is golden brown, about 4 minutes.
Next, stir the flour into the garlic and oil. Cook and stir for 3 minutes until smooth and bubbly. Slowly stir in the remaining tomatoes. Break up the larger tomato pieces using a spoon. Add the dried Italian seasoning, salt and pepper to taste.
Reduce heat to low and simmer the tomato sauce until thickened.
When the meatloaf is done, top with a portion of the tomato sauce and the shredded mozzarella cheese. Return to the oven for 5 - 10 minutes until the cheese is bubbly.
Remove meatloaf from the oven and let rest for 10 minutes. Slice and serve with additional tomato sauce.