Preheat the oven to 200ºC / 400ºF / Gas Mark 6.
Grease and flour two large baking sheets; set aside.
Place a medium saucepan over high heat and add butter, salt and water.
Bring to boil whisking constantly and remove from heat when it reaches a boil.
Add flour all at once and beat vigorously until the mixture comes away from the sides of the pan.
Return the saucepan to low heat and continue beating for one minute.
Transfer the dough to a heavy mixer and put on medium speed.
Add eggs one at a time and then beat in 50g of cheese.
Turn mixer on high to add the maximum amount of air to the batter.
Spoon batter into large piping bag with open coupler.
Pipe batter into 4 cm rounds onto baking trays spacing about 4 cm apart.
Sprinkle rounds with remaining cheese.
Bake 20-25 minutes until puffed and golden.