Add crumb mixture to the meat along with pancetta, egg, nutmeg, cloves, fennel and 2 cloves of finely chopped or grated garlic. Mix very well to combine. Drizzle a little EVOO over combined mixture just before you begin to roll balls. Form medium-sized balls about 2 inches wide and set onto a parchment lined baking sheet.
Raise heat on the pan you cooked pancetta in to medium and add 2 additional tablespoons of EVOO, a couple turns of the pan. Add onions, season with salt and pepper and cook 8 minutes, stirring occasionally. Add remaining 2 cloves of garlic and crushed red pepper flakes, stir 2 minutes more, then add tomato paste and stir 1 minute until fragrant. Add wine and reduce a couple of minutes; then stir in tomatoes, bring sauce to a bubble then reduce heat to simmer.
Place the meatballs in oven and roast 12 minutes or until golden and cooked through.
Salt pasta water and cook pasta to al dente. Add reserved starchy cooking water to a serving bowl just before draining pasta. Add pasta to serving bowl and toss with butter if using, half of the sauce.
Add meatballs to remaining sauce and toss to coat. Serve meatballs with pasta in shallow bowls, a scoop of ricotta garnished with chopped fresh thyme for mixing-in on top.
Serve with celery, arugula and flat-leaf parsley salad dressed with lemon juice and EVOO, salt and pepper or other green salad of choice.