Gâteau Saint-Honoré with Caramel Choux and Vanilla Cream

Pastry cream. in a pan off the heat, whisk the yolks with the sugar, cornflour and salt until smooth, then gradually whisk in the milk. Set over medium heat and whisk constantly until thick, then let it bubble gently for 1 min; it will pass 85 °C. Sieve into a bowl, whisk in the butter and vanilla, press cling film onto the surface and chill at least 3 h.

Base. heat the oven to 200 °C (180 °C fan) and line both trays. Cut a 23 cm round of puff pastry using the plate, lift it onto one tray and prick it all over with the fork. Chill while you make the choux. Pricking the pastry stops the middle puffing up too much.

Choux. bring the butter, water, milk, sugar and salt to a rolling boil, take off the heat and tip in all the flour. Beat until smooth, then stir over low heat for 1-2 min until the paste forms a ball and leaves a film on the pan. Cool 4 min, then beat in the eggs a little at a time until glossy; the paste should fall from the spoon in a thick V.

Pipe. with the 1.5 cm nozzle, pipe a ring of choux 1 cm in from the edge of the pastry round. On the second tray pipe 16 balls about 3 cm across, spaced well apart.

Bake. bake the base for 30-35 min and the balls for 22-25 min, without opening the door for the first 20 min, until both are deep golden and feel light. Poke a hole in the bottom of each ball with the skewer and cool everything on the rack.

Fill the puffs. beat the cold pastry cream until smooth. Using the 6 mm nozzle, fill each puff through the hole until it feels heavy, using about half the cream. Keep the rest chilled.

Caramel. put the sugar, water and lemon juice in the small pan and stir once to wet the sugar. Boil without stirring, swirling the pan now and then, until it turns a medium amber, about 170 °C, then dip the base of the pan in cold water for 2 s to stop it cooking. Hot caramel burns badly, so work carefully and keep children away. Lemon juice helps stop the sugar crystallising as it boils.

Glaze and fix. holding each puff with the tongs, dip its top in the caramel and set it caramel side up on the oiled paper. Then dip the base of each puff in caramel and press it onto the choux ring, side by side, all the way round. Rewarm the caramel gently if it thickens.

Finish. spread the remaining pastry cream inside the ring. Whip the cold cream with the icing sugar and vanilla to firm peaks and pipe it in rosettes, close together, to cover the pastry cream completely. Chill and serve within 4 h.