Preheat a fan forced oven to 180C / 355F (200C/400F for no fan). Line two half sheet baking trays with baking paper or (for best results) silicone baking mats. If using baking paper stick some of the choux pastry under the baking paper to help it stick to the baking tray.
Heat butter in water - Add the water, butter, and sugar to a large saucepan. Place on medium heat and stir until the butter has melted and it begins bubbling around the sides.
Add flour - Once bubbles appear, turn off the heat and add the flour. Stir immediately using a wooden spoon until a dough forms.
Cook dough - Turn the heat back on medium high and mix continuously for 2-3 minutes. If using a stainless steal pan you’ll notice a film of dough forming on the bottom. This won’t happen with a non-stick pan.
Add eggs - Take off the heat and allow to cool for 10 minutes. In the meantime, whisk the eggs together. Add 1/4 of the eggs into the cooled dough and mix until well combined. Add the next 1/4 and continue until all eggs are in the dough. The dough will be sticky to the touch and when stretched in between two fingers, won’t break. If the dough breaks, add another tbsp of whisked egg and test again. If the dough is runny, there are too many eggs, start again.
Pipe dough - Add the filling to a piping bag fitted with a large round tip and pipe 2 tbsp blobs onto lined baking trays. You’ll get 18 blobs on each tray. These will puff up and spread into decent sized profiteroles.
Smoothen out profiteroles - Dip your finger into some water and dab the pointy end of the choux pastry to smoothen it out. This will help them rise properly and not burn.
Dust with sugar - Dust the tops with powdered sugar (this helps them keep their shape and slightly sweetens them).
Bake - Bake both trays for 40 minutes. Allow to cool in the oven with the door slightly open for 10-15 minutes before taking them out so they hold their shape and don’t deflate.