Mint Chocolate Checkerboard Cookies

Bahan-bahan (24 porsi)

• 2 and 1/2 cups (313g) all-purpose flour (spooned & leveled)
• 1/2 teaspoon baking powder
• 1/2 teaspoon salt
• 1 cup (16 Tbsp; 226g) unsalted butter, softened to room temperature
• 1 cup (200g) granulated sugar
• 1 large egg + 1 egg yolk, at room temperature* (save extra egg white)
• 1 and 1/2 teaspoons pure vanilla extract
• optional for topping: 1 Tablespoon (15ml) water and 1/4 cup (50g) coarse sugar
• 1 teaspoon peppermint extract
• optional: 1 drop green food dye
• 2 Tablespoons (10g) unsweetened natural or dutch-process cocoa powder
• 1 Tablespoon (15ml) milk
• optional: 1 teaspoon espresso powder