Pre-heat the oven to 220°C/200°C/Gas 7. Line a baking sheet with baking parchment and draw 4 circles, about 10cm across, on the underside of the paper.
Sift the flour onto a sheet of baking parchment. Put the water, milk, salt, sugar and butter in a pan and bring slowly to the boil over a medium heat, until the butter has just melted.
When the water is bubbling, remove quickly from the heat, tip in the flour all at once and beat vigorously until it forms a dough that leaves the side of the pan clean.
Return to the heat and cook for at least five minutes.⏱ 5 min
Leave to cool slightly, then gradually beat in the lightly beaten eggs, beating well between each addition until the dough is smooth and glossy.
Spoon the dough into a piping bag and snip a generous hole.
Pipe 4 thick rings onto the lined baking sheet, using the circles as a guide and piping the rings in one motion.
Lightly brush the top of the choux with egg wash, then sprinkle over flaked almonds.
Bake in the oven for 10-15 minutes then reduce the heat to 180°C/160°C fan/Gas 4 and bake the choux for a further 10 minutes until they are well risen and golden.⏱ 25 min
Once baked, remove from the oven and immediately slice the rings in half horizontally and return to the oven to dry out for approximately 3-4 minutes.⏱ 4 min
For the praline, melt the caster sugar in a pan over a medium heat until the sugar has melted to a caramel. Add the hazelnuts and swirl to coat the hazelnuts in the caramel. Pour out onto a silicon sheet and leave to cool and harden.
Once cool, blitz the praline to a fine dust in a mini food processor.
For the filling, pour the cream into a large mixing bowl. Slice the vanilla pod in half and scrape out the seeds. Add the vanilla seeds to the cream and whip the cream to soft peaks. Spoon into a piping bag fitted with a star nozzle.
Sprinkle half the praline onto the bottom halves of the choux rings, then pipe a generous amount of cream in a circular motion over the praline.
Sprinkle the remaining praline over the cream and place the choux lids on top.
Dust with icing sugar and serve.