Cut a deep pocket in the fillets, but only so far that they are still connected. Pepper all around, salt is not necessary, the flavor comes from the bacon and the filling.
Mix the ingredients for the filling in a bowl and distribute them on the opened fillets, fold up again and wrap 3 - 4 slices of bacon around each. Heat a little oil in a pan and fry the fillets all around for approx. 8-10 minutes over a mild heat.
In the meantime, preheat the oven to approx. 150 ° convection. Grease a baking dish with a little clarified butter, put the fillets in it, place the rosemary sprigs on top and cook for another 25 minutes. Remove, slice and serve.