Boil spaghetti according to packet instrutions till Aldante. Strain and keep aside. Reserve some pasta water.(add warm pasta to pesto) i have use spaghetti yet penni, faralle, fussili can also serve well.

Wash nicely fresh basil leaves. Put in food processor.add walnuts, garlic, cheese and grind. Add olive oil in between. Process to a fine creamy paste. If it's slight grainy then no issue but no big chunks of walnuts appear.

Take out pesto in a bowl. Mix salt, black pepper and lemon juice. Taste and adjust the seasoning.add little pasta water in pesto to thin out so it coats spaghetti nicely and makes a glossy pesto.

Take pesto in a deep bowl. Add warm spaghetti in bowl and toss gently so as spaghetti absorbs most of the pesto and should not breakup.

Pesto can be make with spinach, mint, parsley, beet greens, broccli. Adding lemon juice helps to retain colour of pesto. Do not cook basil pesto, bx basil turns black with heat. Use freshly Aldante spaghetti.it's heat will be ok for basil pesto. Do not reheat the basil pesto as it will turns to dark colour. Use at room temperature.