Blackberry Peppermint Chocolate Striped Cookies

INGREDIENTS

• 130 g (1 cup) blackberries (frozen is ok)
• 90 g (1/3 cup plus 1 tablespoon) granulated white sugar, divided
• 226 g (8 oz or 2 sticks) unsalted butter at room temperature
• 115 g (1 cup) confectioners’ (powdered) sugar
• 1 teaspoon salt
• 1/2 vanilla bean
• 1 egg
• 1/2 teaspoon red food coloring
• 385 g (2 3/4 cup) all purpose flour
• 100 g (1/2 cup) granulated white sugar
• 1 teaspoon peppermint extract
• 280 g (2 cup) all purpose flour
• 25 g (1/4 cup) natural cocoa powder
• 35 g (1/4 cup) onyx black cocoa powder
• 10 g (1 tablespoon) instant coffee
• 1 large egg white
• 1 tablespoon of water
• 1/4 cup sparkling white sugar crystals