Gâteau Saint-Honoré

Instructions

1. Make the pastry cream: bring the 500 ml whole milk and the vanilla bean pod and seeds to a simmer. Whisk the egg yolks, 80 g granulated sugar and cornstarch in a bowl, whisk in the hot milk (pod removed), return to the pan and cook over medium heat, whisking, until thick and boiling; keep boiling 1 minute (at least 160°F / 71°C). Spoon 200 g into a small bowl for the puffs; cover both portions with plastic wrap pressed on the surface and refrigerate 1 hour.
2. Heat the oven to 400°F (200°C). Roll the all-butter puff pastry 1/8 inch (3 mm) thick, cut a 9-inch (23 cm) circle, set it on a lined sheet and prick it all over with a fork. Chill for about 30 minutes while you make the choux.
3. For the choux pastry, bring the water, 60 ml whole milk, 50 g unsalted butter and salt to a full boil. Off the heat, stir in the all-purpose flour, then stir over medium heat 2 minutes until the dough pulls away and leaves a film on the pan. Cool 1 minute in a bowl and beat in the eggs a little at a time until glossy and falling from the spoon in a thick V-shaped ribbon.
4. With a 1/2-inch (1.5 cm) plain tip, pipe a ring of choux 1/2 inch (1 cm) inside the edge of the pastry disc, and a loose spiral of choux in the center. On the second sheet, pipe about 16 small 1-inch (2.5 cm) mounds.
5. Bake both sheets 15 minutes, then lower to 350°F (175°C). Remove the small puffs when golden, crisp and light, 8 to 12 minutes more, and the base when the pastry is deep golden and the choux ring is dry, 20 to 25 minutes more. Poke a small hole in the bottom of each puff and cool everything completely on racks, about 30 minutes.
6. Whisk the reserved 200 g cold pastry cream smooth and pipe it into the small puffs through the holes.
7. For the caramel, cook the 200 g granulated sugar and 60 ml water in a small heavy saucepan over medium heat without stirring until light amber, about 340°F (170°C), 8 to 10 minutes; dip the base of the pan in cold water to stop the cooking. Carefully dip the top of each filled puff in the caramel and set it caramel side up to harden, then dab the bottom of each in caramel and stick the puffs side by side on top of the choux ring.
8. For the Chiboust, sprinkle the powdered gelatin over the 30 ml cold water and let it swell 5 minutes. Gently rewarm the remaining pastry cream in a saucepan, whisking, until warm to the touch, about 120°F (50°C); whisk in the gelatin until it dissolves.
9. Make an Italian meringue: boil the 150 g granulated sugar and 40 ml water to 245°F (118°C). Meanwhile whip the egg whites to soft peaks; with the mixer running, pour in the hot syrup in a thin stream and whip until glossy and just warm, about 5 minutes. Fold the meringue into the warm pastry cream in three additions until smooth.
10. Right away, spoon the Chiboust into a piping bag with a Saint-Honoré tip (or a large star tip) and pipe it in the center of the cake in overlapping rows or swirls inside the ring of puffs. Refrigerate until set, at least 2 hours, and serve the same day.