- 15 tablespoons unsalted butter, cut into pieces
- 2 teaspoons pure vanilla extract
- 2 cups all-purpose flour
- 1 teaspoon baking powder
- 1/2 cup granulated sugar
- 1/2 teaspoon salt
- 1 egg white, lightly beaten
- 1/3 cup sanding sugar
Melt butter over medium heat. Continue to cook, stirring constantly, until deep golden brown, about 11 minutes. Immediately pour butter into a large bowl, and let cool to room temperature, about 10 minutes. Stir in vanilla.
Whisk together flour, baking powder, granulated sugar, and salt. Gradually stir into butter mixture. Form dough into a ball, then roll into a 14-inch-long log (about 1 1/2 inches in diameter). Wrap in parchment, and refrigerate until firm, about 1 hour.
Preheat oven to 350 degrees. Brush dough with egg wash, and roll in sanding sugar. Slice into 3/8-inch rounds, and transfer to parchment-lined baking sheets. Bake until light brown and firm, 15 to 17 minutes. Let cool completely on baking sheets on wire racks.