- Vegetable oil, cooking spray
- 2 cups all-purpose flour
- 1 1/4 teaspoons coarse salt
- 8 ounces (2 sticks) unsalted butter, softened
- 3/4 cup packed light-brown sugar
- 12 ounces milk chocolate, melted
- 1 cup creamy peanut butter
- Coat a 9 1/2-inch square baking pan with cooking spray. Line with parchment, leaving a 2-inch overhang on 2 sides, and coat parchment with spray.
- Sift flour and salt into a medium bowl. Beat butter with a mixer on medium-high speed until fluffy, 3 to 5 minutes. With the mixer running, add sugar, and beat until pale and fluffy, about 2 minutes. Reduce speed to low. Add flour mixture, beating until just incorporated. Press dough evenly into pan. Cover, and refrigerate until firm, about 20 minutes.
- Preheat oven to 300 degrees. Bake shortbread until golden brown and firm in center, 45 to 50 minutes. Let shortbread cool in pan on a wire rack.
- Place a basket-weave mat, trimmed to fit pan, on a rimmed baking sheet, and spread melted chocolate evenly on mat. Refrigerate until firm, about 45 minutes.
- Use parchment to unmold shortbread from pan, and trim edges to create a square. Spread peanut butter evenly on shortbread. Carefully center chocolate, mat side up, on top of peanut butter, and gently peel off mat. Cut shortbread into 1 1/2-inch squares. Shortbread will keep, covered, for up to 3 days.
You will need a basket-weave mat (we used an 8"-by-16" rubber texture mat in basket weave (PA 01-6), $12, from chineseclayart.com) to imprint the chocolate with the woven motif. To make the squares without a mat, spread the melted chocolate atop the peanut butter layer, and refrigerate until firm, about an hour.