1. Heat oven to 400 degrees. Place the pecans on a baking sheet. Toast in oven until golden and fragrant, 8 to 10 minutes. Let pecans cool.

2. In the bowl of an electric mixer fitted with the paddle attachment, cream butter and sugar on medium speed until light and fluffy, 2 to 4 minutes. Add egg and vanilla; incorporate.

3. In a medium bowl, whisk together flour, cornmeal, baking powder, and salt. On low speed, add flour mixture to butter mixture. Mix until combined, about 30 seconds.

4. Transfer dough to a clean work surface, and divide into four equal portions. Place one portion between two 12-inch-square pieces of parchment. Roll out dough to a 3 1/2-by-9-inch rectangle. Repeat with the remaining 3 portions dough. Transfer to baking sheets; chill at least 10 minutes.

5. In the bowl of food processor, process pecans, cinnamon, and brown sugar until nuts have been finely chopped, 12 to 15 seconds. Transfer mixture to a medium bowl.

6. Remove top pieces of parchment from dough. Brush one lightly with egg white; sprinkle 1/4 cup pecan mixture over top. Brush second rectangle lightly with egg wash. Invert second rectangle over first; remove parchment on top. Repeat layering process, leaving top rectangle uncoated. Trim to a 3 1/4-by-8 1/2-inch brick. Wrap; chill overnight.

7. Heat oven to 350 degrees. Line two baking sheets with parchment. Cut the brick into 1/4-inch-thick rectangles; place rectangles on baking sheets, spaced 2 1/2 inches apart.

8. Bake biscuits until light golden, 12 to 15 minutes. Transfer to a wire rack to cool. Bake or freeze remaining dough. Store in an airtight container up to 2 weeks.