Preheat oven to 200 C. Pour into the pan a glass of cold water and add half a pack of diced butter. Put on the fire. Once the water boils, pour 180 grams of flour and ? teaspoon of salt and a wooden ruler stir the resulting mass. Knead the dough until then, until it becomes to move away from the walls of the pan. Remove from heat, cool and add in turn 4 large eggs, mixing thoroughly weight. With pastry syringe or spoon lay out the dough into balls with walnuts on a baking sheet, the laid paper baking. Put the pan in the preheated oven for 25-30 minutes, and in any case do not open the door until the profiteroles are baked.
Meanwhile, in a bowl whisk 200g mascarpone cheese with 2 tablespoons of powdered sugar and 1 teaspoon vanilla sugar. Ready fill profiteroles with cream pastry syringe and pour melted chocolate.