To make the pesto, blitz the basil, spinach, macadamias, cavolo nero (optional), half the oil and a large pinch of salt in a food processor. You can make it as smooth or as chunky as you like.
Add the rest of the oil and some freshly cracked pepper. Place the blended mixture in a bowl and stir in the cheese. Season to taste.
Bring a pot of salted water to boil and cook the pasta until al dente. Drain and reserve a cup of the cooking water.
In a large frying pan, warm half the pesto with some oil. Add the spaghetti, the rest of the pesto and as much cooking water as you like. Toss gently, transfer to bowls or plates and top with grated Grana Padano, cracked pepper and basil.
