Pink Grapefruit Sandwich Cookies

INGREDIENTS

• :
• 1½ cups all-purpose flour
• ¾ cup cake flour
• 1 teaspoon baking powder
• ½ teaspoon salt
• 1 cup granulated sugar
• Zest of 1 pink grapefruit
• ½ cup unsalted butter, at room temperature
• 2 egg yolks
• ¼ cup pink grapefruit juice (freshly squeezed)
• 2¾ cups powdered sugar
• 2 teaspoons pink grapefruit zest
• 3 tablespoons pink grapefruit juice (freshly squeezed)
• 1 small drop red food coloring (optional)