Saint-Honoré with caramel cream puffs and diplomat cream

Mix the gelatin with 15 g cold water and leave for 5–10 minutes to swell. In a bowl, mix the yolks with 60 g sugar and the cornstarch. Bring the milk and vanilla almost to a boil. Gradually whisk half into the yolks, then pour everything back into the saucepan with the remaining milk. Heat, whisking vigorously. Once the thick cream starts bubbling clearly, cook for about 2 minutes more, still whisking. Remove from the heat, add the swollen gelatin and 8 g butter, and stir until dissolved.

Transfer the cream to a shallow dish and cover with plastic wrap touching the surface. Once it stops steaming heavily, refrigerate for about 90 minutes, until completely cold. It chills while you prepare and bake the pastry. On baking paper, prepare a puff pastry disc 24 cm across and about 3 mm thick, weighing out 180 g after trimming. Set the trimmings aside, outside this recipe. Do not dust with extra flour; roll between sheets of paper if needed. Prick the disc with a fork and keep in the fridge while you make the choux pastry.

In a small saucepan, bring 100 g water to a boil with 40 g butter and the salt. Remove from the heat, add all the flour at once and stir vigorously. Heat again for 1–2 minutes, beating until the dough forms a ball and pulls away from the sides. Transfer to a bowl and stir for a few minutes until it stops steaming and is just warm. Add the beaten egg in small amounts, beating thoroughly after each addition. Stop when the mixture is smooth and glossy and falls from the spatula in a broad V-shaped ribbon; you may not need all 100 g egg. Set any unused egg aside, out of the cake.

Preheat the oven to 200°C with conventional top and bottom heat. Transfer the choux pastry to a piping bag with a round tip or a suitably cut corner. Pipe a ring about 1 cm thick on the cold base, about 1 cm in from the edge. Divide the remaining mixture into 12 small round puffs on a second baking tray lined with baking paper, leaving about 5 cm between them. Use all the remaining mixture, dividing it as evenly as possible; gently smooth any pointed peaks with a teaspoon.

Bake the base with its ring first: 15 minutes at 200°C, then 25–30 minutes at 180°C, until the ring is golden and the base is well baked underneath too. After removing it, heat the oven back to 200°C. Bake the small puffs for 10 minutes at 200°C, then about 20–25 minutes at 180°C, until golden, light and dry on the surface. Do not open the oven early in either bake; if the puffs are still pale or soft, bake a few minutes longer. Transfer both batches to racks and leave to cool completely, about 60 minutes after the last tray comes out.

Make sure the pastry cream is completely cold. Whisk it thoroughly, or beat briefly with a mixer, until smooth again. Whip the cold cream until it forms defined but flexible peaks. Mix about one third into the pastry cream to loosen it, then gently fold in the rest with a spatula. Do not add whipped cream to warm pastry cream. Keep the finished cream in the fridge until filling.

Make a small hole in the bottom of each completely cooled puff. Put some of the cream in a piping bag with a narrow tip and fill all 12 puffs until noticeably heavier, without splitting their sides. Reserve the remaining cream for the center of the cake. Keep the filled puffs and cream briefly in the fridge while you make the caramel.

Combine 180 g sugar and 50 g water in a small saucepan. Heat until the sugar dissolves, then boil without stirring with a spoon until light amber; gently tilt the pan if needed. Remove from the heat. Hold the puffs gently with tongs, briefly dip their tops into the caramel and place them cap-side up on paper. The caramel is very hot: do not dip your fingers in, and do not add water to it. If it thickens too much, carefully warm it over low heat. Wait for the caps to harden.

Set the baked base with its ring on a serving stand. With a teaspoon, put a little liquid caramel on the bottom of each puff and attach all 12 to the ring, spacing them evenly around it. Do not touch the hot caramel. Once the puffs are secure, pipe the remaining diplomat cream into the center in a simple spiral or rows of soft waves. Unused caramel stays out of the cake; do not pour it over the cream or base.

Refrigerate the finished cake for about 30 minutes. It is best served the same day; keep it in the fridge until slicing. Cut carefully with a sharp serrated knife so you do not crush the crisp base and caramel cream puffs. The planned time includes chilling the pastry cream alongside preparation and baking, plus separate time for the baked pastries to cool completely and the final dessert to chill.