Prepare the olive cream. Put the butter in a bowl, divide it in pieces and soften it at room temperature. In the meanwhile stone the olives, rinse them repeatedly under running water, drain them and then dry them with a very clean tea towel.Slice them very finely (or mix them in a food processor). Rinse the capers under running water, drain and dry them then slice them finely. Work the butter until a foamy cream is reached, add the chopped olives, the capers, the grated lemon zest, the oil, the lemon juice, a pinch of salt and pepper.Stir constantly until a well-blended smooth cream is obtained. Cook the fettuccine in plenty of boiling water. Pour 2 tbsp of cooking water of the pasta over the olive cream and stir well. When al dente drain the fettuccine, mix them with the olive cream, mix well and serve.