• Bring a large pot of salt water to a full boil. Add pasta and cook until it’s just shy of al dente (usually 2 minutes less than the shortest time on package directions). It’ll finish cooking as it bakes.
• Reserve ¼ cup of pasta water then drain the pasta and rinse it with cold water to stop the cooking process.
• Drizzle the olive oil into a large skillet over medium heat then add the ground beef, onions, (optional) mushrooms and grated garlic. Season with salt and pepper and cook until the beef is no longer pink, breaking up the clumps with a wooden spoon or spatula.
• Lower the heat to medium, fold in the tomato paste, Italian seasoning, reserved pasta water, tomato sauce and parsley then cook 3-4 minutes.

  Stir ricotta cheese into the sauce then add the cooked pasta stirring well to combine.

Assembly:

• Preheat oven to 350 degrees.

  Grease a 9×13 baking dish with butter or cooking spray. Add half of the mostaccioli to the baking dish. Top with half of the mozzarella then add the rest of the mostaccioli, the remaining mozzarella and parmesan cheese.
• Transfer to the preheated oven. Bake uncovered 25-30 minutes or until the cheese is melted and starting to brown. Serve warm.