The word “Gerbeaud” is never translated. It’s assumed that everyone who orders it knows that it is thin, tender layers of sweet yeast dough alternating with apricot jam and ground walnuts, covered with a shiny chocolate glaze. This is an unusual yeast dough; the small amount of yeast and high proportion of sugar keep the dough from rising high, so don’t expect this to be a puffy yeast pastry. Thanks to Gerbeaud’s executive chef, Sandor Kovacs, who shared the prized recipe with me.
1ounce (½cube) fresh compressed yeast or 3¾teaspoons (about 1¾envelopes) active dry yeast
½cupmilk (heated to 105° to 115°F if using dry yeast)
14tablespoons (1¾sticks) unsalted butter, cut into ½-inch cubes, chilled
To make the dough: Crumble the yeast into the milk in a glass measuring cup. Let stand 3 minutes, then stir to dissolve. Mix in the egg yolks and vanilla.
Measure the flour, the sugar, and the salt into the bowl of a heavy-duty standing mixer fitted with the paddle blade. Add the butter and mix on low speed until the mixture resembles coarse cornmeal. Add the yeast mixture and mix, adding more milk if necessary, to form a very stiff, sticky dough. Transfer to a lightly floured work surface and knead for 2 to 3 minutes. The dough will remain sticky and resemble a sugar cookie dough; do not add more flour to the board. Wrap in plastic wrap and refrigerate for 1 hour.
Meanwhile, prepare the filling: Process the walnuts and sugar together in a food processor fitted with the metal blade until very finely chopped.
Butter and flour a 13 X 9-inch baking dish and tap out the excess flour. Divide the dough into three equal portions. Roll out one portion of dough into a 13 X 9-inch rectangle and transfer to the pan, pressing it into the corners to fit. Spread with half of the preserves and sprinkle with half of the walnut mixture. Roll out another layer of dough, fit into the pan, and spread with the remaining preserves and walnuts. Top with the third layer of rolled dough. Cover with plastic wrap and let stand in a warm place for 1 hour (the dough’s rising will be barely perceptible).
Position a rack in the center of the oven and heat to 350°F. Pierce the top layer of dough well with a fork. Bake until the top is golden brown, 30 to 35 minutes. If the top browns too deeply, cover loosely with aluminum foil.
Cool on a wire rack for 15 minutes. Run a sharp knife around the edge of the pan. Holding a long rack over the pan, invert and unmold the cake and cool completely, leaving the cake upside down.
To make the icing: Bring the chocolate, sugar, and water to a boil in a small saucepan over medium heat, stirring often. Boil until an instant-read thermometer reads 220°F, 3 to 4 minutes. Remove from the heat and stir in the butter to melt. Cool the icing until slightly thickened and lukewarm, but still pourable.
Place the cake on the rack over a baking sheet. Pour all the icing over the top of the cake and spread evenly with an offset metal spatula, letting the excess icing drip over the sides. (Don’t bother smoothing the sides, as they will be trimmed off.) Refrigerate the cake until the icing sets.
Using a thin, sharp knife dipped in hot water, trim the sides of the cake. Cut the cake in half lengthwise, then crosswise into 12 bars. Serve at room temperature.