Cut the brown onions in half and use a mandoline or onion slicer to slice them into thin pieces. Soak the slices in a bowl of water to help reduce the sharpness and minimize tears.
Separately, roughly chop ¼ of a brown onion, the carrot, and celery into small pieces. Add them to a food processor with a generous amount of EVOO and a splash of water. Blend into a smooth mixture.
Cut the large pieces of beef chuck and pork rashers into small, even-sized chunks, then set them aside.
Place your Dutch oven over medium heat, then add about 3 tablespoons of EVOO and pour in the blended soffritto mix. Cook for around 10 minutes, stirring occasionally using a wooden spoon.
Add the chopped meat to the pan and stir to combine with the soffritto. Increase to medium-high heat and brown the meat. Cover with a lid and let it cook in its own steam for 2 minutes.
Add salt and pepper (not too much), stir, and toss in the 4 bay leaves. Put the lid back on and let it simmer for another 2 minutes.
Pour in the white wine to deglaze the pan and let it cook uncovered for about 5 minutes to allow the alcohol to evaporate.
Add in the sliced onions. Gently mix to combine and bring some of the meat to the surface. Season again with salt and pepper to taste. Cover with a lid and cook on low heat for 4 hours, stirring every 30 mins.
After 4 hours, remove the lid and continue to cook the sauce uncovered for another 2 hrs on low heat to let the liquid reduce and concentrate the flavor.
Once the sauce is thick and jammy, gently squash the meat using a spoon or spatula to pull it apart. Remove and discard the bay leaves.
Bring a large pot of water to a boil. Add 1 tablespoon of salt, then cook the ziti according to the package instructions. Stir occasionally to prevent sticking. Reserve 1 cup of pasta water before you drain the pasta.
In a medium-sized pan, add as much Genovese ragù as you like. Once the pasta is al dente, transfer it to the pan and stir well to coat. If needed, add a splash of reserved pasta water to loosen the sauce and create an even creamier texture then toss to emulsify.