Tear the leaves of basil and place in a tall blending jug. Add all the other ingredients with the exception of the salt. Blend with a hand blender/mixer until the mixture is soft and sludgy. You can add a little more oil if it feels a little dry, but don't overdo it. Season with a little salt. This will keep covered in the fridge for a day or so, but it's best made and served straight away. You can put the water on to boil and make the pesto. By the time your water has boiled you will have made the pesto and washed up all the utensils.
PS. You can use a food processor for this, but I find you will need to double or triple the quantities to get a good result. You can freeze any leftover pesto. It will keep for about 1 month.
What can go wrong? Try not to overblend the pesto as it ruins the delicate basil flavour. That's why the ground almonds work so well, because you don't have to whizz the mixture very long. Don't go mad with the olive oil. Too much oil will make the sauce very greasy. You can always drizzle a little more oil over the pasta just before serving.
Quick Meals
I can't believe how much my kids love this and how incredibly quick it is to prepare. We used to buy the ready made version at Waitrose which was nice, but this is so much nicer, fresher and made with pure extra virgin olive oil. I haven't done a price comparison, but I'm sure mine is more economical given that I am using fresh basil, lovely parmesan and olive oil. If you look at many of the ready made varieties many use other oils and lots of preservatives.
Because my children request this dish all the time and I don't always have fresh basil on hand to make it, I've taken to freezing portions in small plastic containers. This works very well and makes an instant delicious out of the freezer meal in less than 10 minutes (or the time it takes for the water to boil and the pasta to cook through). Oh and another thing, try making pesto rice. This makes a nice change from pasta. All you need do is make some rice (basmati is nice and very quick) then swirl in a tablespoon or two of fresh pesto. Dish up and watch it disappear.