We took the classic French one-layer cake (our editor-in-chief’s favorite!) from round to rectangle. A tender, golden crust encases a surprise center of thick, velvety Custard Filling, a defining factor of the original gâteau Basque, with a thin layer of fresh blueberries to bring brightness to every slice.
- ¾ cup (170 grams) unsalted butter, softened
- 1⅔ cups (333 grams) granulated sugar
- 3 large eggs (150 grams), divided
- 2 large egg yolks (37 grams)
- 3¼ cups (406 grams) all-purpose flour
- 2¼ teaspoons (11 grams) baking powder
- 1¼ teaspoons (3.75 grams) kosher salt
- Custard Filling (recipe follows)
- ¾ cup (128 grams) fresh blueberries
- 1 tablespoon (15 grams) water
- Garnish: confectioners’ sugar
- In the bowl of a stand mixer fitted with the paddle attachment, beat butter and granulated sugar at medium speed until fluffy, 3 to 4 minutes, stopping to scrape sides of bowl. Add 2 eggs (100 grams) and egg yolks, one at a time, beating well after each addition.
- In a medium bowl, whisk together flour, baking powder, and salt. With mixer on low speed, gradually add flour mixture to butter mixture, beating just until combined. Turn out dough, and shape into a disk. Wrap in plastic wrap, and refrigerate until firm, about 2 hours or up to overnight.
- Line a 9×5-inch loaf pan with parchment paper, letting excess extend over sides of pan.
- On a heavily floured surface, roll dough to ¼-inch thickness. Cut a 9-inch square from dough. Gently transfer to prepared pan, placing in bottom and up sides. Cut 2 (4½x3-inch) rectangles from dough, and place widthwise on either ends of prepared pan. Press dough together in corners to seal. (See Note.)
- Reroll remaining dough to ¼-inch thickness, and cut a 9×5-inch rectangle from dough. Transfer to a sheet of parchment paper, and refrigerate.
- In bottom of pan, place blueberries in a single layer. Spoon Custard Filling on top of blueberries, smoothing flat, and tap pan on counter 3 times to release air bubbles. Trim dough to ⅛ inch above Custard Filling.
- In a small bowl, whisk together 1 tablespoon (15 grams) water and remaining 1 egg (50 grams). Brush top of dough in pan with egg wash. Place 9×5-inch dough rectangle on top, pressing around edges to seal. Freeze until set, 30 to 45 minutes.
- Preheat oven to 400°F (200°C).
- Brush dough with egg wash.
- Bake for 20 minutes. Reduce oven temperature to 350°F (180°C), and bake until top is deep golden brown and a wooden pick inserted in top (but not in custard) comes out clean, about 40 minutes more, covering with foil after 20 minutes of baking to prevent excess browning. Let cool in pan for 15 minutes. Using excess parchment as handles, remove from pan, and let cool completely on a wire rack. Just before serving, garnish with confectioners’ sugar, if desired. Refrigerate in an airtight container for up to 4 days.
- 2½ cups (600 grams) whole milk
- ½ cup (100 grams) granulated sugar, divided
- 1 vanilla bean, split lengthwise, seeds scraped and reserved
- 6 large egg yolks (112 grams)
- ⅓ cup (40 grams) cornstarch
- In a medium saucepan, heat milk, ¼ cup (50 grams) sugar, and reserved vanilla bean seeds over medium heat until steaming.
- In a medium bowl, whisk together egg yolks, cornstarch, and remaining ¼ cup (50 grams) sugar. Whisk hot milk mixture into egg yolk mixture. Return mixture to saucepan, and cook, whisking constantly, until mixture starts to boil. Cook, whisking constantly, until cornstarch flavor is cooked out, 2 to 3 minutes. Remove from heat, and strain through a fine-mesh sieve into a medium heatproof bowl. Cover with plastic wrap, pressing wrap directly onto surface of custard to prevent a skin from forming. Let stand at room temperature until just warm, about 30 minutes. Use immediately.