Combine the water and butter in a saucepan and bring to a boil. When it boils, remove from the heat and sift in the flour. Whisk by hand until incorporated, then bring back to the heat for 1-2 minutes to evaporate excess liquid, if present.
Let the mixture cool for 15 minutes. Aside whisk the egg by hand. When the mixture has cooled pour in the egg and whisk by hand until incorporated. Transfer the mixture to a piping bag.
Line a baking tray with baking paper. Pipe 10-12 puffs making sure to space them out enough so they have room to double in size as they bake. Smooth down the peaks with a lightly moistened finger.
Bake in the preheated oven at 180°C (350°F) fan-forced for 25-30 minutes (this depends on the size of your puffs). When the puffs look golden brown, turn off the oven and let the puffs rest 10 minutes inside with a small opening in the oven door. Let cool to room temperature before filling them.
Combine the raspberries and powdered sugar and blend. Combine the raspberry purée and whipping cream and whip at medium speed until thick enough to pipe. Transfer the raspberry cream to a piping bag fitted with a star attachment.
Cut off the choux pastry puff tops, keeping them next to each puff. Pipe the raspberry whipped cream inside the pastry puff hollow moving the pastry bag upwards. Gently place the top piece of the pastry puff over the cream, like a lid. Finish with a sprinkle of powdered sugar on top.