First, dice up the onion then sauté the onion and garlic together. Right before removing the pan from the heat add in the Italian seasoning to allow the dried herbs begin to rehydrate with the onions and garlic. Set to the side to cool and continue to the next step.
In a large bowl, add in the ground meat. Toss in the beaten eggs, breadcrumbs, buttermilk, salt, pepper, Worcestershire sauce and lastly the cooked onions and garlic. Mix everything to the point where it's evenly combined. Cover the bowl then refrigerate for 30 minutes.
Preheat the oven to 350℉.
Line a loaf pan and add in the mixture for the meatloaf. Press it down and shape it to remove any possible air pockets. Or you can shape the meatloaf by hand and place on a sheet pan.
Place the meatloaf in the oven for 45 minutes then remove and top with the marinara sauce. Place the meatloaf back in for 20 minutes or until the meatloaf is fully cooked in the center.
Allow to cool for 15-20 minutes and just before serving sprinkle the grated parmesan across the top then slice and enjoy.