Preheat oven to 400 degrees and prepare a baking dish with cooking spray.
Wash and dry the tomatoes, slicing off the tops and removing the white core. You can also remove some of the seeds as they can sometimes be bitter.
In a small bowl, combine all of the ingredients for the topping and divide evenly between the four tomatoes.
Bake uncovered until the tomatoes are tender and the breadcrumbs are golden. If they aren't getting golden enough, just move to the top rack for 5 minutes. Keep and eye on them so nothing burns.