Combine butter, salt, sugar and water. Heat butter and sugar in a pan and bring to a boil. Take off the heat, add flour all at once and beat with a wooden spoon until the dough comes off from the sides of the pan. Leave to cool for 5 mins, then beat in the eggs one by one until you have a stiff, glossy mixture. Pipe blobs of the mixture onto a baking tray. Bake at 220°C for 18-20 mins until well risen and golden brown. Remove the profiteroles from the oven and cut a small slit in the base of each one so they don’t collapse. Cool on a wire rack.