The secret to the rich flavor and beautiful, deep-red color of this sauce is lots of red wine. This sauce uses almost an entire bottle of wine and a long cooking time to meld the flavors together. Serve tossed with al dente spaghetti or pappardelle and fresh grated Parmigiano-Reggiano.
In a large pot, heat the olive oil over medium-high. Add the chopped onions and sweat the onions for a minute or two. Then, add the minced garlic and the eggplant. Cook the vegetables, occasionally stirring with a wooden spoon, until the eggplant and onions are translucent and soft, about 3 to 5 minutes.
Next, add the ground beef and brown the meat. Once the meat is browned after 5 or 8 minutes, remove the pan from the heat and drain off the excess fat. Return the pan to medium high heat, and season the meat and vegetables with salt, red pepper, black pepper, cinnamon, and bay leaf. Stir to mix in the spices. Add the red wine, and bring to a boil. Allow the wine to reduce by half about 10 minutes.
Once the wine has reduced, add the tomatoes. Reduce the heat to medium or medium low to maintain a slow simmer. Cover the pot with a lid and allow the Bolognese to simmer for about 2 to 4 hours. Add water or wine if the sauce becomes too dry. Re-season the sauce with salt and pepper according to taste, and serve with pasta cooked al dente.