Heat broiler to high. Place bell peppers on a baking sheet and broil about 10-12 minutes, turning 2-3 times, until charred all over. Set onto a plate or bowl to cool, then slice in half. Then, preheat the oven to 425.
Toss together the basil, oregano, rosemary, thyme, and pinch of red pepper flakes. Set aside.
Bring a large pot of salted water to a boil. Cook pasta according to package directions. Drain.
In a bowl, stir together the 1 1/2 cups of marinara sauce, the pasta, and parmesan cheese.
Spread remaining 1/2 cup marinara sauce on the bottom of a large, deep-sided baking dish. Arrange bell pepper halves on the dish. Spoon pasta mixture evenly into each half. You can stuff them pretty well! Top with mozzarella cheese. Sprinkle seasoning blend overtop. Arrange pepperoni slices over each pepper.
Bake peppers for 15 minutes until cheese is melted, gooey, and bubbling. Serve warm.