Place bread in a food processor; pulse 10 times or until coarse crumbs measure 1/2 cup; set aside.
Cut top off each tomato. Scoop out pulp, leaving shells intact. Discard tops and pulp.
Place tomatoes on a jelly roll pan lined with foil. Sprinkle tomatoes with salt and pepper.
Combine breadcrumbs, basil, olives, and garlic in a small bowl. Spoon 1/4 of breadcrumb mixture into each tomato shell. Drizzle each tomato with 1/2 teaspoon oil.
Broil 3 to 4 minutes or until thoroughly heated.