Fill a large pot with water and add a pinch of salt. Bring to a boil, add the pasta, and cook according to package instructions (8-10 minutes) until al dente.

In a frying pan, heat a splash of olive oil over medium heat. Add the chopped kale and cook until wilted (about 3-5 minutes). Remove from heat and set aside.

If using fresh peas, add them to the pasta during the last 2 minutes of cooking. If using frozen peas, add them later in the blender.

Once the pasta is cooked, drain it and return it to the pot.

In a blender or food processor, combine wilted kale, cooked peas, chopped walnuts, minced garlic, and Parmesan cheese (if using). Add a drizzle of olive oil.

Blend until smooth. If too thick, add olive oil or a splash of water.

Pour the pesto over the cooked pasta. Toss until well coated.

Squeeze half a lemon over the pasta and season with salt and pepper.

Serve warm in a bowl or dish, optionally topping with extra walnuts or Parmesan cheese.