Preheat the oven to 200C/Fan180C/Gas Mark 6. Bring a saucepan of water to the boil with a pinch of salt and add the fusilli. Cook for 10 minutes, or according to pack instructions. Reduce the cooking time by 2 minutes if you prefer your pasta to be al dente.
Place the garlic bread slices on a baking tray. Place in the oven and cook for 6-7 minutes, or until golden.
Heat the oil in a large saucepan and add the onion and anchovies, if using. Cook for 3-5 minutes or until soft and opaque. Add the olives and sauce. Swirl out the jar with 2-3 tbsp cold water and add to the olives and sauce. Bring to the boil, reduce the heat and simmer for 4-5 minutes.
Add a couple of tablespoons of the fusilli water to the sauce. Stir to combine. Drain the fusilli and stir into the sauce with the pesto. Place in a serving bowl. Season. Serve with the garlic bread slices and grated cheddar cheese.