1. Make dough: In a food processor, pulse flour, baking powder, and salt. Add cold butter; pulse until mixture resembles coarse crumbs with pea-sized butter bits.
2. Add wet ingredients: With motor running, add sugar, egg, and vanilla. Pulse just until dough begins to clump.
3. Rest: Turn dough onto a lightly floured surface. Shape into a rough rectangle. Wrap in plastic; chill 30 minutes.
4. Laminate (create layers):
   • Roll dough into a 12×8″ rectangle.
   • Sprinkle half the chocolate over surface. Fold dough in thirds like a letter.
   • Rotate 90°, roll again into 12×8″. Sprinkle remaining chocolate. Fold in thirds again.
   • Wrap and chill 1 hour (or up to 2 days).
5. Slice & bake: Preheat oven to 350°F (175°C). Line baking sheets with parchment.
   • Slice dough into ¼”-thick rectangles or rounds. Place 2″ apart on sheets.
   • Sprinkle with flaky salt if desired.
6. Bake 12–15 minutes, until golden at edges but centers look soft.
7. Cool on pan 5 minutes before transferring to a rack.

💡 Pro Tips:
– Keep butter cold—this creates steam pockets for flakiness.
– For extra layers, repeat folding process once more before chilling.
– Store in an airtight container up to 5 days—they stay crisp!

Prep Time & Nutrition (per cookie, makes 16):