1. Preheat the oven to 200°C. Line a baking tray with greaseproof paper.
2. Heat the water and butter in a saucepan until the butter has melted.
3. Beat in the flour, sugar and salt until the mixture is smooth, then continue to cook for 2-3 minutes. Remove the pan from the heat and beat in the eggs, one at a time, until smooth and glossy.
4. Set aside to cool, then spoon the dough into a piping bag fitted with a medium sized plain nozzle.
5. Pipe a large circle onto the baking sheet. Bake for 30 minutes until golden and crispy. Cool.
6. Split the pastry in half, mix the puree and cream together and fill the pastry. Top with the other half.
7. Place the sugar into a non-stick frying pan and heat until a deep golden caramel colour, poor over the top of the Paris Brest, sprinkle with flaked almonds and decorate with marron glacés.