Cook Pasta: Cook the pasta according to package instructions. Drain and transfer to a large bowl.
Preheat oven to 350 F degrees.
Make Sauce: Crumble the sausage meat into a large skillet over medium heat and brown, stirring often for about 5 minutes, until it's no longer pink.
Add the onion, pepper and continue cooking for another 3 minutes, or until the onion and pepper have softened and the onion is translucent.
Stir in the tomatoes, oregano, tomato paste, basil, thyme, fennel seeds, salt and pepper. Add the chicken broth and stir. Bring to a boil, reduce the heat and cook for another 20 minutes, stirring often as needed.
Stir in the peas. Remove the sauce from heat.
Toss penne with sauce: Pour the sauce over the cooked pasta and stir. Stir in about 1 cup of cheese.
Assemble: Transfer the pasta to a large casserole dish. Top with remaining mozzarella cheese.
Bake: Transfer the casserole dish to the preheated oven and bake until the cheese has melted and the casserole is bubbling, for about 20 minutes.
Serve: Garnish with parsley or basil if desired and serve warm.