Cut butter into pieces. Put 125 ml water, salt and butter in a pot and bring to the boil. Add flour at once and mix well. Stir over low heat until the dough comes off the bottom of the pot in a lump. Remove the pot from the stove. Stir in eggs one by one. Grate half of the cheese and stir in
Pour the dough into a piping bag with perforated spout and spray small tuffs onto 2 baking trays lined with baking paper. Bake the cream puffs sheet by sheet in a preheated oven (electric cooker: 200 °C/ convection oven: 175 °C/ gas: see manufacturer) for approx. 25 minutes until golden brown
Open the oven door and let the cream puffs rest in the switched off oven for about 5 minutes. Cut the remaining Gruyère into small strips. Cut small notches into the cream puffs and put the cheese into the notches. Serve warm