For the sauce: In a large Dutch oven, heat the olive oil over medium-high heat. Add the chopped onions, and cook until it is slightly softened, about 4 minutes. Add the tomatoes, rinse out the tomato cans with 4 cups water, and add that as well. Add the salt, bay leaves, and red pepper flakes. Bring it to a simmer, and cook, uncovered, until slightly thickened, about 20 minutes.

Meanwhile, for the meatballs: In a large skillet, heat the olive oil over medium-high heat. When the oil is hot, add the onion. Cook until it is almost softened, about 6 minutes, then add the eggplants and season with salt. Cover, and cook until the eggplant and onion are tender, about 10 minutes. Scrape everything onto a sheet pan to cool.

In a large bowl, mix the cooled eggplant with the beef, sausage, bread crumbs, parsley, grated cheese, and eggs until the mixture just holds together. Form into about forty 2-inch meatballs on parchment-lined sheet pans.

Add the meatballs to the simmering sauce, and simmer until the meatballs are cooked through and the sauce is flavorful, about 35 to 40 minutes, stirring occasionally with a wooden spoon, to make sure the meatballs on the bottom don’t stick.

This makes a big batch, and it is ideal to keep in the refrigerator or freeze to be used for future meals. If you don’t want to make such a big batch, you can easily halve everything.