Ingredients
1/2 c. (110 g.) butter, room temperature
1/2 c. (100 g.) caster sugar or granulated sugar
1 1/4 c. (170 g.) cake flour, sifted, plus more for rolling
3 tbsp. polenta
3 tbsp. unsweetened cocoa powder
1 tsp. baking powder
1 large egg
1 tsp. vanilla extract
1/4 c. (60 g.) butter
1/2 c. plus 3 tbsp. (130 g.) granulated sugar
2 tbsp. unsweetened cocoa powder
1/2 tsp. vanilla extract
Preparation
Step 1Preheat oven to 320°F (160°C). Line 2 large baking sheets with parchment paper or nonstick silicone liners.Step 2In a food processor, cream butter and caster sugar. Add flour, polenta, cocoa powder, and baking powder and continue to process until mixture resembles fine breadcrumbs. Add egg and vanilla and continue to process until a smooth dough forms; do not overprocess or biscuits will be very hard.Step 3Transfer dough to a medium bowl and knead with your hands until smooth and combined. On a lightly floured surface, roll dough to a square about 1/4" (0.5 cm) thick, dusting with flour to prevent sticking. Using a ruler, cut out 24 (2") squares, rerolling scraps if necessary. Step 4Arrange dough on prepared sheets and prick with a fork to make a pattern. Bake until slightly puffed and firm, 12 to 14 minutes. Let cool on baking sheet 5 minutes, then transfer to a wire rack and let cool completely.
Step 1In a small saucepan over medium heat or in a heatproof bowl in microwave, melt butter. Add granulated sugar, cocoa powder, and vanilla and stir to combine.Step 2Spread a generous amount of filling on flat side of 12 squares. Place a second square flat side down on top and lightly press down to stick together.
