Frosted Peppermint Sugar Cookie Bars

Bahan-bahan (16 porsi)

• ¾ cup softened unsalted butter
• 1 cup granulated sugar
• 1 large room-temperature egg
• 1 teaspoon vanilla extract
• 2 cups all-purpose flour
• ½ teaspoon baking powder
• ½ teaspoon salt
• 1 (15-ounce) can vanilla frosting
• ½ teaspoons peppermint extract, (optional)
• 7 crushed candy canes