Trim the leeks, and slice into 2cm rounds. Peel the garlic cloves and add both to a small saucepan with 150ml of olive oil. Place onto medium-low heat and let gently sizzle until both are soft, 15-20 mins. They shouldn’t colour, if they are, decrease the heat. Once softened, let cool down.

Meanwhile, add the walnuts into a dry pan on medium heat, cook the walnuts until toasted, 2-4 mins, then let cool down completely.

Add the cooled walnuts and Parmesan into a blender and blend until finely broken down, transfer into a small bowl. Add the leek mixture into the blender with 90ml of infused olive oil and blend until smooth, stir into the walnut mixture. Wash the blender.

Remove the stem off the chillies and place into the blender with the remaining 60ml of infused oil, blend until smooth. Finely mince the parsley and pick the oregano leaves. Pour the chilli oil into a frying pan, place on medium heat and cook for 2-3 mins. Add the herbs and cook for 2-3 mins until dark green. Remove from the heat and let cool down. Zest ¼ of the lemon into the oil and season with lemon juice.

Bring a pot of salted water to the boil. Once boiling, cook the pasta according to package instructions. Toss the spaghetti and pesto together with a little pasta water until creamy. Taste and season with salt.

Share between bowls and drizzle over the chilli oil.