Preheat the oven to 200C/180C Fan/Gas 6. Line three baking sheets with baking parchment.

In a heavy saucepan, melt the cubed butter in 250 ml water over medium heat. Bring to a boil carefully, then remove from heat; quickly add sifted flour and stir vigorously until a soft ball forms. Return to low heat and cook for 3–5 minutes, stirring constantly. Let it cool slightly.

Transfer mixture to a mixer bowl with whisk attachment or use a hand mixer. Gradually whisk in the beaten eggs, one at a time, until smooth and shiny paste forms. Fill a piping bag fitted with a 1½ cm plain nozzle with the choux mixture.

Pipe twelve small mounds of mixture onto each baking sheet (total 36). Smooth tops with a wet finger. Bake for 10 minutes, then reduce oven to 190C/170C Fan/Gas 5 and bake an additional 10 minutes until golden brown. Pierce each bun with a skewer to release steam, return to oven for 5 minutes to dry out. Cool on wire rack.

Heat milk in a heavy-based pan to boiling, then let cool for 30 seconds. Whisk egg yolks with caster sugar until pale. Add cornflour, cinnamon, and nutmeg, whisk to combine.

Gradually pour warm milk into egg mixture, whisking continuously, then return to pan. Cook over medium heat, whisking continuously until thick and boiling for 1 minute. Remove from heat, transfer to bowl, cover with cling film and cool.

Break milk chocolate into a heatproof bowl. Heat double cream until simmering, pour over chocolate and stir until smooth. Cool until thick enough to drizzle.

Spoon melted white chocolate into a small piping bag fitted with writing nozzle. Pipe 12 snowflake shapes onto baking parchment and let set.

Whip double cream to soft peaks, then fold into cooled crème pâtissière. Fill a piping bag with this mixture and pipe into cooled choux buns.

In a pan, boil caster sugar with 5 tablespoons water until golden or 170C on a sugar thermometer. Remove from heat, plunge pan into cold water to thicken slightly.

Arrange 14 choux buns in a circle, all touching. Place 10 buns inside to create a second smaller circle. Dip one side of each bun into caramel and stick to adjacent bun, forming a bond. Continue until both circles are joined.

Dip bases of remaining 12 buns in caramel and place on top of the double circle wreath to complete the shape.

Line a baking sheet with silicone paper. Reheat caramel gently, add small amount of red food colouring, then stir in hazelnuts. Remove hazelnuts and place individually on the silicone paper to cool and harden.

Drizzle one quarter of the chocolate ganache over the assembled wreath. Transfer to serving plate and decorate with white chocolate snowflakes and caramel-coated hazelnuts. Serve immediately.