Preheat the oven to 350 degrees F.
Arrange the bread cubes on a baking sheet and lightly toast in the oven, about 10 minutes. Let cool.
Increase the oven to 400 degrees F.
Remove the cores from the top of the tomatoes and cut the top off the tomato 1/4 of the way down. Reserve the tops. Slice enough of the bottom off each tomato, so it stands up, but don't cut through to the seed. (If you cut too deep, patch the hole with the piece you have just sliced off, by placing it in the bottom after you've hollowed it out.)
Using a melon baller, carefully scoop the inside of the tomatoes out, taking care not to penetrate the sides and create holes. Collect the balls of pulp and chop coarsely. Press the juice and seeds through a strainer. Add the strained juice to the chopped pulp.
In a bowl, mix together the tomato pulp, Parmesan, olives, olive oil, parsley, basil, oregano, and garlic. Toss with the bread cubes and season with salt and pepper. Let the mixture sit until the bread cubes have soaked up most of the moisture.
Season the interior of each tomato with salt and black pepper. Stuff each tomato with 1 bread cube and as much as herb olive mixture that you can pack in. Top with the reserved tomato tops and stick a toothpick through the center of the top to keep it from sliding off while it bakes. Place the stuffed tomatoes in a roasting pan that has been drizzled with olive oil. Drizzle the tops of tomatoes with olive oil and season with salt and pepper. Roast until bubbling and tender, about 30 to 40 minutes.