Strip the kale from the stalks. Blanch it in boiling salted water for 2 minutes, lift it out, refresh it in cold water and squeeze it out well.
Cook the wholewheat spaghetti in the same water until al dente, according to the packet instructions. Save a cup of the cooking water before draining.
Toast the walnuts in a dry frying pan for 3 minutes. Grate the zest of the lemon and squeeze the juice.
Blend the kale, three quarters of the walnuts, the hard cheese, garlic, olive oil, lemon juice, salt and pepper with a little cooking water to a smooth pesto.
Toss the spaghetti with the pesto and a little cooking water until evenly coated.
Serve the pasta with the lemon zest, the remaining walnuts and the chilli flakes.
Good to know
Pesto works with kale too: briefly blanched, it turns mild and stays green, and walnuts and lemon round it off.
Swaps
Hard cheese → nutritional yeast (vegan). Walnuts → almonds. Wholewheat spaghetti → lentil pasta (gluten-free, also provides protein). Kale → baby spinach (no blanching).
Cooking tips
Well-squeezed kale won't make the pesto watery. The starchy cooking water helps the pesto cling to the pasta.
Storage
Covered with oil, the pesto keeps for 4 days in the fridge; the pasta with pesto is best freshly made.
Allergens
Contains gluten, milk and walnuts (tree nuts); no egg. Suitable for children and in pregnancy.
Frequently asked questions
How long does kale pesto pasta keep in the fridge?
Covered with oil, the pesto keeps for 4 days in the fridge; the pasta with pesto is best freshly made.
