Put half the garlic into a pestle and mortar or a food processor. Add a bit more garlic if you like, but I tend to stick to about half a clove. Pound or pulse this with the fresh basil leaves and the pine nuts to a fine purée. Turn out into a bowl and add the Parmesan. Gently stir in and add a little olive oil until smooth and spreadable. If you want, add more Parmesan to adjust the taste.

Grill or toast the slices of bread, rub with the remaining halved clove of garlic, then drizzle with a little extra virgin olive oil. Spoon over the pesto and season well to taste.

Serve immediately.