Preheat oven to 350 degrees and prepare 13x9 inch baking dish with cooking spray.
Combine Italian sausage, ground beef and chopped onion in a large, deep skillet and mash it into smaller pieces. Cook over medium-low heat until the meat is fully cooked through and no pink remains. About 5-7 minutes.
Add marinara sauce, bay leaf, Italian seasoning, garlic, grated Parmesan cheese and basil to the same skillet along with the cooked meat. Stir to combine and cover and bring to a simmer. Let simmer for at least 15 minutes.
While the sauce is simmering, cook your dried pasta according to package instructions until al dente. Be careful not to overcook the pasta.
Combine meat sauce, cooked pasta and half of the shredded cheese in a large bowl and stir until combined. Add to a 13x9 inch baking dish and top with the remaining shredded cheese. Cook on the middle rack until cheese is melted and sauce is bubbling. About 20 minutes. Serve warm with optional garnish and enjoy!
Leftover Storage: Store leftovers in an airtight container in the fridge for up to 4 days.
Freezer Option: Cooked mostaccioli can be stored in a freezer bag or container for up to 3 months.
Make Ahead Option: Follow recipe prep instructions and store uncooked and combined mostaccioli in the fridge for up to 24 hours. When ready to eat follow recipe baking instructions.
Crockpot Option: Baked mostaccioli can be placed in the crockpot on WARM to keep fresh for hours. Stir occasionally to avoid the pasta from sticking to the bottom.
Re-warming Instructions: Microwave: Place pasta in a microwave fast bowl and cover. Warm for 60 seconds or until warmed through. Oven: Place in a large baking dish and bake at 350 for 15 minutes until warmed through. Crockpot: Place in crockpot on LOW for 1 hour. After 1 hour switch to WARM and stir.