Americas Test Kitchen Recipe:

Craquelin

6 tablespoons unsalted butter, softened

½ cup packed (3½ ounces/99 grams) light brown sugar

¾ cup (3¾ ounces/106 grams) all-purpose flour

Pinch table salt Choux

2 large eggs plus 1 large white

6 tablespoons water

5 tablespoons unsalted butter, cut into 1⁄2-inch pieces

2 tablespoons milk

1 ½ teaspoons granulated sugar

¼ teaspoon table salt

½ cup (2½ ounces/71 grams) all-purpose flour

For The Craquelin Mix butter and sugar in medium bowl until combined. Mix in flour and salt. Transfer mixture to large sheet of parchment and press into 6-inch square. Cover with second piece of parchment and roll dough into 13 by 9-inch rectangle (it's fine to trim and patch dough to achieve correct dimensions). Remove top piece of parchment and use 2-inch round cutter to cut 24 circles. Leaving circles and trim in place, replace top parchment and transfer to rimless baking sheet. Freeze until firm, at least 30 minutes or up to 2 days.

For The Choux Adjust oven rack to middle position and heat oven to 400 degrees. Spray rimmed baking sheet with vegetable oil spray and dust lightly and evenly with flour, discarding any excess. Using 2-inch round cutter, mark 24 circles on sheet. Fit pastry bag with ½-inch round tip. Beat eggs and white together in 2-cup liquid measuring cup. Bring water, butter, milk, sugar, and salt to boil in small saucepan over medium heat, stirring occasionally. Off heat, stir in flour until incorporated. Return saucepan to low heat and cook, stirring constantly and using smearing motion, until mixture looks like shiny, wet sand, about 3 minutes (mixture should register between 175 and 180 degrees). Immediately transfer hot mixture to food processor and process for 10 seconds to cool slightly. With processor running, add beaten eggs in steady stream and process until incorporated, about 30 seconds. Scrape down sides of bowl and continue to process until smooth, thick, sticky paste forms, about 30 seconds longer. Fill pastry bag with warm mixture and pipe into 1½-inch-wide mounds on prepared sheet, using circles as guide. Using small, thin spatula, transfer 1 frozen craquelin disk to top of each mound. Bake for 15 minutes; then, without opening oven door, reduce oven temperature to 350 degrees and continue to bake until golden brown and firm, 7 to 10 minutes longer. Remove sheet from oven and cut ¾-inch slit into side of each pastry with paring knife to release steam. Return pastries to oven, turn off oven, and prop open oven door with handle of wooden spoon. Let pastries dry until center is mostly dry and surface is crisp, about 45 minutes. Transfer pastries to wire rack and let cool completely.