We make the Avocado Pesto: In a blender add the garlic, lemon juice, basil leaves, parmesan, salt, pine nuts (save some for garnishing), olive oil, avocados. Blend well.
In a pot, add 3 litres of water and let it boil. Add the stock and salt. Stir and add the pasta. Let the water boil again, decrease the heat to medium and boil for 8 minutes. Strain the pasta but save 1 cup of their broth. Return the pasta to the pot. Add the Avocado Pesto and, if needed, the broth. Stir well.
Serve the pasta with the cherry tomatoes and the roasted pine nuts.