Gâteau St. Honoré can be made in lots of different ways. The foundation is usually made of puff pastry, short crust, pâte à choux or a combination thereof. Huh? A combination? Yup. The most typical combo is a base of puff pastry with a layer of choux on the top, which is what I’m going to do. I happen to have a large ball of puff pastry scraps in the freezer and they’ll be perfect for the job (since I want the richness but not necessarily all the height). A normal sheet of puff pastry will work great, too. You’ll just need to prick it (“dock” it) with a fork.
As for the filling, it can be whipped cream, pastry cream, ganache, chiboust (pastry cream plus Italian meringue), or — you guessed it — just about any combination of those, put down in layers. I’m going for the chiboust, mainly because it’s going to be hot where I’m taking this, and I want something that’ll hold up for an hour or so before it’s eaten. Also we haven’t done it before. You’ll need:
Preheat your oven to 450 degrees Fahrenheit. On a floured board, roll out the puff pastry into a thin sheet about 11″ across. Lay a 10″ circular for on top and cut around it with a pizza cutter, making a circle. Transfer the circle to a parchment-lined baking sheet pan, dock it with a fork and put the pan in the refrigerator to rest.
Prepare the choux and load it into a pastry bag fitted with just the collar, no tip. Remove the puff pastry from the refrigerator and pipe a line of choux around the edge of the circle. Next, on a separate parchment-lined sheet, pipe about 18 small puffs. With the remaining batter, pipe a spiral of choux in the center of the tart. Bake both sheets for 10 minutes (with a wooden spoon handle stuck into the oven door to allow moisture to escape), then lower the temperature to 400. After about five minutes the puff should be done. Remove them from the oven and allow them to cool. The larger pastry might take the full 15. When it’s good and dark, remove it from the oven and let it cool completely.
The base and puffs will keep for a day or overnight at room temperature. They can even be frozen if you wish, carefully covered in plastic.
When ready to assemble, load the pastry cream into a pastry bag fitted with either a long Bismarck tip, or some other skinny tip that will allow you to poke through the bottom of the puffs and fill them. Then, fill the cream puffs (but not to much).
Next prepare the caramel and leave a low flame under it so it doesn’t cool completely and harden. Have a parchment-lined baking sheet nearby. When the caramel is ready, CAREFULLY dip the tops of the cream puffs into the hot caramel and set them — caramel side down — on the parchment-lined sheet. When the last puff has been dipped, return to the first one (it should be cool by now). Dip the bottoms of the puffs in caramel and stick them to the edge of the base, touching each other, all the way around.
Once that’s done, you’re ready to make the chiboust. Load it into a pastry bag without either a tip or a coupler, and pipe large blobs of the chiboust into the center in rows. Refrigerate the pastry until you’re ready to serve it, up to a full day.