1. Bring a pan of water to the boil then add the pasta shells. Cook for 2 minutes less than the cooking instructions suggest. The pasta shells should be al dente. Drain and rinse in cold water and set aside.
2. Add the oil to a 10" cast iron skillet placed over a medium heat. When the oil is hot add the crushed garlic and chilli flakes. Cook for 1 minute then add the spinach. Cook for 3 minutes or until the spinach has wilted.