Meatballs with tomato & green olive sauce

INGREDIENTS

• 500g lean pork mince
• 1 red onion , grated or very finely chopped
• a pinch dried chilli flakes
• ½ tsp fennel seeds , crushed in a pestle and mortar
• Parmesan , grated to make 4 tbsp
• olive oil
• 3 garlic cloves , sliced
• 2 x 400g tins plum tomatoes
• 4 cloves
• 12 green olives , pitted and quartered
• a small bunch basil , shredded
• 300g tagliatelle
• a knob butter