Coat a nonstick baking sheet with cooking spray. Place tomatoes, cut side up, on baking sheet.
Combine mayonnaise, mustard, and red pepper in a small bowl; stir well. Set aside.
Combine breadcrumbs, parsley, and cheese.
Spread about 1 teaspoon mayonnaise mixture on cut sides of each tomato. Top each tomato evenly with breadcrumb mixture. Bake at 400° for 12 to 15 minutes or just until tomato is tender. Remove from oven, and let stand 5 minutes before serving.