Coffee-Spice Shortbread with Crystallized Ginger

INGREDIENTS

• 1 cup (2 sticks) chilled unsalted butter, cut into 1/2-inch cubes
• 1 teaspoon vanilla extract
• 1/2 cup powdered sugar
• Special equipment: 2 9-inch-diameter tart pans with removable bottom
• 1/2 teaspoon salt
• 2 tablespoons plus 2 teaspoons ground coffee beans
• 1 1/2 teaspoons ground cinnamon
• 3/4 cup (packed) dark brown sugar
• 2 teaspoons (or more) water
• 2 teaspoons ground ginger
• 2 3/cups all purpose flour
• 6 tablespoons chopped crystallized ginger
• 1 teaspoon ground cardamom