Pierce each tomato with the tip of a pairing knife. On a small baking sheet, combine the tomatoes, garlic, basil, salt and 3 tablespoons olive oil. Toss to coat. Roast until the tomatoes begin to blister, 30 minutes. Set aside to cool.
Increase the oven temperature to 425 degrees F.
On a lightly floured board, roll out the pizza dough to a 1/4-inch thickness. With a cookie cutter or the tip of a sharp knife, cut out six 5-inch hearts. Transfer to a baking sheet, and bake until lightly puffed and starting to brown, 12 minutes. Let cool slightly.
Slice the hearts in half horizontally, like a sandwich bun. Divide the mozzarella and the roasted tomato mixture among the bottom halves, and sprinkle with the Parmesan. Cover with the top halves. Brush the tops with 2 tablespoons olive oil, and sprinkle with the oregano.
Bake until the cheese is melted and the tops are golden, 5 minutes. Serve warm, drizzled with additional olive oil if desired.