Preheat your oven to 190C / 325F. Line a large baking tray with baking paper. Set aside.
To a large saucepan, add the water, butter, salt and sugar and stir until mixture bubbles and butter melts. Take off the heat and add the flour. Mix using a wooden spoon immediately. Once the mixture forms a dough, place back on medium high heat and stir for about 4 minutes or until the dough begins sticking to the bottom of the saucepan. Take off the heat and allow to cool for 10 minutes.
You can mix this dough by hand using a wooden spoon. I added mine to the bowl of a stand mixer fitted with a paddle attachment. And began mixing on low speed for 30 seconds before adding the first egg. Allow the egg to mix in before adding the next egg. You may not need all 4 eggs. What you’re looking for is a shiny, glossy and smooth dough mixture that when stretched between two fingers, does not break. See notes below for more information.
Place the dough mixture into a piping bag fitted with a medium round tip.
Place a round 6” cake tin or plate on top of the baking paper and use a pen to trace around it. Dab the corners of the baking paper with choux pastry dough and turn over onto the baking tray. This will help it stick and stop it from flying around in the oven.
Pipe a ring of dough around the traced circle. And then pipe another one directly on top. Brush with egg wash (1 egg whisked with 1 tbsp water or milk) and then sprinkle with flaked almonds. Bake for 35-40minutes. Once baked allow to cool completely in the oven. This will help prevent it from collapsing.
Once baked and cooled, use a serrated knife to carefully cut in half. It will be hollow inside. Pipe some pastry cream in the hollowed-out part of one half of the pastry rings. Then use a spoon or offset spatula to smoothen out flat. Then pipe swirls of pastry cream. Place the second half on top and finish with a dusting of powdered sugar.