Sterilise a jar by putting it through a hot dishwasher cycle or washing it in hot, soapy water, rinsing well and drying it in a hot oven for 10 minutes.
Bring a large pan of salted water to the boil. Add the spring onions and garlic and cook for 3 minutes, until they're soft. Add the kale and cook for no more than 40 seconds, until it's bright green and floppy. Don't overcook it as it will lose that lovely bright-green colour.
Lift out the kale with a slotted spoon and put it onto a plate. Lift out the garlic and spring onion (don't discard the cooking water) and blitz them in a food processor with the almonds. Add the olive oil, parsley, basil, chilli flakes and blitz again.
Squeeze the excess water out of the kale and add it to the food processor too, blitzing, followed by the lemon juice and zest, and Parmesan. Season with black pepper and salt to taste, and stir. Store the pesto in the sterilised jar, covering it with a layer of olive oil to seal in the freshness.
Cook the linguine in the same water that you blanched the kale in for about six to seven minutes, or until al dente. Drain, reserving a splash of the pasta water, return to the pan and stir in generous tablespoons of the pesto and the reserved pasta water, and season with freshly ground black pepper and more Parmesan.