Heat the olive oil in a large, wide sauté pan. Add the garlic and anchovies and cook over a medium heat for 2 minutes until the ingredients have almost melted into the oil. Add the chillies and oregano and cook for a further 1 minute.
Cook the pasta according to the instructions on the packet. Meanwhile, add the tomato paste to the sauté pan. Cook for 1-2 minutes, stirring frequently, then add the cherry tomatoes and olives. Bring to the boil, then turn down the heat to medium and cook on a steady simmer, stirring occasionally, for 5-6 minutes until thickened.
Add the spinach to the sauce. Stir and allow to wilt slightly. Drain the pasta and add to the sauce. Season and serve with a scattering of basil and some parmesan shavings.