Cut the tops off the tomatoes and lightly give them with a gentle squish or use a teaspoon to remove some seeds. Carefully scoop the flesh into a bowl and season the hulled tomatoes with salt and pepper. Combine the flesh with Pepper Jack, garlic and onion; re-stuff the tomatoes.
In another bowl, combine the breadcrumbs with oregano, fresh cilantro or parsley and Parm. Pile topping on the stuffed tomatoes, packing the breadcrumbs in, and spray with cooking spray. Place on a baking sheet and roast in a 425°F oven or put in a grill roasting pan and grill for 8-10 minutes until golden and the cheese is melted.