Slice the pepper and set aside a handful for serving.
Finely chop the onion, celery, tomato, courgette, garlic and chilli (if used).
Heat the oil in a saucepan. Add the onion and celery and ( under cover) gently sauté until soft. Add the garlic, (chilli), courgette and tomato and cook for another 5 minutes until the tomatoes are soft.
Add the roasted pepper to warm through. Season with salt and pepper and add the fresh herbs. Using a stick blender, blend into a textured paste. Stir in the pepper slices that you've set aside and keep warm under cover.
Meanwhile, cook the pasta according to the pack instructions. Drain and combine with the pepper sauce. Warm through and serve.
You can serve it with some Parmesan shavings or toasted pine nuts if you like.