Put the red pepper, onion, chilli ( if used) and garlic (with the skin on) on a baking sheet, drizzle with some olive oil and roast in the oven for 30 minutes until the veggies are soft. Alternatively, you can barbecue or grill them.
Transfer them to a bowl, cover and let them cool.
Remove the skin and place the flesh of the onion and pepper vegetables into a small food processor. Squeeze the flesh out of 4 garlic cloves and add to the veggies (the rest can be used for other meals).
Deseed the chilli, remove the skin and add the flesh to the veggies.
Add the basil leaves, lemon juice and a drizzle of olive oil. Blitz until you get a course paste. Season with salt and pepper to your liking. Taste and adjust the flavours if needed.
Meanwhile, cook the pasta according to the packet instructions. Drain and put them back into the pan. Add the paste and mix well.
Serve with plenty of freshly ground pepper and grated Parmesan, if liked.