Place mince, half the garlic, onion and half the basil in a large bowl. Season. Mix to combine well using clean hands. Roll a tablespoon of mince mixture into a ball. Repeat to make 20 meatballs.
Heat oil in a large non-stick frypan over medium-high heat. Cook meatballs, in batches, for 3-4 minutes or until browned. Set meatballs aside on a plate. Add remaining garlic and chilli to pan and cook for 1-2 minutes. Add passata, stir well, bring to a boil then reduce heat to a simmer. Return meatballs to pan and cook for 6-8 minutes, stirring occasionally, or until sauce thickens. Add remaining basil and stir through.
Cook polenta according to packet instructions. Add butter and 3/4 of parmesan. Season and stir until butter melts.
Top polenta with meatballs. Spoon sauce over meatballs and sprinkle with remaining parmesan and basil leaves. Serve with beans and broccoli.
Other herbs such as thyme, chives, parsley or mint would also be delicious.
Swap onion for 1 eschallot, finely chopped, if desired.
Serve with a green salad with lemon dressing instead of steamed vegetables.