In a large pot of boiling salted water, cook fusilli until al dente, then drain.

Meanwhile, in a medium skillet, heat the olive oil. Add the leek and cook over moderate heat until softened, about 7 minutes.

Add the spinach and cook until it wilts, about 5 minutes. Remove from heat and set aside.

In your serving dish, whisk the oil, parmesan, lemon juice, zest and salt and pepper.

Add in the pasta and stir to coat. Stir in the leeks and spinach. Garnish with a bit more zest and parmesan. Serve.