Preheat the oven to 425 degrees F.
In a large bowl, using your hands, combine the beef, Parmesan, breadcrumbs or oatmeal, parsley and eggs. Grate in (or mince and add) the garlic and add some salt and pepper. Do not overwork it, just lightly mix together, or the meat will become compacted and dense.
Butter a shallow, round baking pan of about 11 inches diameter and turn the meat into it, pressing the mixture lightly with your fingers to cover the bottom as if the seasoned ground meat were your pizza crust.
Make sure you've drained as much runny liquid as possible out of your can of diced tomatoes, then mix the tomato with the garlic-flavored oil, oregano and some salt and pepper, and spread, using a rubber spatula, lightly on top of the meat base. Arrange the mozzarella slices on top, and then put in the oven for 20 to 25 minutes, by which time the meat should be cooked through and lightly set and the mozzarella melted.
Remove from the oven and let it sit for 5 minutes, then adorn with some basil leaves and bring it to the table before cutting into wedges, like a pizza.
Reprinted from Nigellissima. Copyright (c) 2012 by Nigella Lawson. Published by Clarkson Potter, a division of Random House LLC. All rights reserved.