Paris-Brest with hazelnut praline cream

1.For hazelnut praline, stir sugar and 40ml water in a saucepan over medium-high heat until sugar dissolves, then brush down sides of pan with a wet pastry brush and bring to the boil, swirling pan as mixture starts to caramelise, until dark caramel (5-6 minutes). Remove from heat, stir in hazelnuts and a pinch of salt with a lightly oiled fork, tip onto a lightly oiled baking tray and stand until set (40 minutes). Coarsely crush praline, then process three-quarters (reserve remaining in an airtight container to serve) in a food processor, scraping down sides occasionally, until a paste forms (5-6 minutes). Store in an airtight container at room temperature until required.

2.Bring milk to a simmer in a saucepan over medium-high heat. Meanwhile, whisk yolks and sugar in a bowl until pale (1-2 minutes), whisk in cornflour, then, whisking continuously, gradually add milk, then return to pan and whisk until simmering and thickened (1-2 minutes). Remove from heat, whisk in three-quarters of the praline paste, transfer to a bowl, cover directly with plastic wrap and refrigerate until chilled (1-2 hours). Whisk hazelnut praline cream to loosen, then fold in whipped cream. Transfer to a large piping bag fitted with a 1cm fluted nozzle and refrigerate.

3.For choux pastry, bring butter, 250ml water and a pinch of salt to the boil in a saucepan over medium-high heat. Remove from heat, quickly stir in flour until smooth, return to heat and beat for 2-3 minutes, then transfer to an electric mixer. Beat for 1 minute to cool slightly, then add eggs, one at a time, beating well and scraping down sides of bowl between additions, until glossy and smooth. Spoon into a piping bag fitted with a 1cm plain nozzle. Draw eight 6cm circles (use a cup or a cutter as a template), then pipe rings of choux pastry around each, sealing ends with a flick of the wrist. Pipe a second ring of pastry around the outside of the first so the rings touch, then pipe a third ring on top where the first two rings meet. Brush lightly with eggwash, scatter with hazelnuts and bake until golden brown and puffed (30-35 minutes). Cool on wire racks.

4.To assemble, halve choux rings horizontally and spread bases with a little hazelnut praline paste. Pipe hazelnut praline cream over the bases in a decorative pattern, scatter with crushed hazelnut praline, sandwich lightly with choux ring tops, dust with icing sugar and serve. These are best eaten on day of making.