First prepare the ingredients. Wash and drain the spinach and then shake it in a cloth to dry it as much as possible. Then, if necessary, take the stalks off the spinach and cut up the leaves, unless they are really small. Open the cans of oysters so that they are ready to use. Then bring a large pan of salted water to boil, drop in the pasta shells and cook them for 10-12 minutes until they are al dente, just cooked but still with a very slight bite to them. As soon as you have put the water on to boil, you should start cooking the other ingredients. Put the olive oil into a large deep frying pan over a high heat. When the oil is very hot add the garlic followed by the spinach. Stir swiftly for barely one minute, just until the spinach has become limp. Lastly, stir in the smoked oysters and their oil. Remove the pan from the heat and season with plenty of black pepper and a little salt if needed. When the pasta is ready, drain and pat the pasta in to a heated serving bowl. Pour the frying pan mixture on top and lightly mix in the pasta. Serve immmediately, with grated Parmesan cheese if like.