Position a rack in the center of the oven; preheat to 475 degrees .
In a small bowl, combine the breadcrumbs and milk; set aside. In a large bowl, combine the meats; season with salt and pepper. Add the ricotta, parsley, 1/4 cup grated cheese, the egg, spices, a fat drizzle of EVOO and the grated garlic. Stir in the moistened breadcrumbs; mix to combine. Divide the mixture into 4 equal portions; divide each portion into thirds and roll each into a large meatball, to make 12 meatballs. Bake on a rimmed nonstick or parchment-lined baking sheet until just cooked through and slightly crispy, 16 to 18 minutes.
Meanwhile, in a large, deep skillet, heat 2 tbsp. EVOO over medium-high. Add the sliced garlic and grated onion, season and stir until fragrant, 1 minute. Add the tomato paste; stir 1 minute more. Add the wine; simmer until reduced by half, about 5 minutes. Add the stock and passata, then reduce the heat to medium-low. Add the meatballs; simmer, gently turning the meatballs, until heated through, about 5 minutes. Serve with sauce, cheese and bread for mopping.