Shamrock Shortbread Cookies (Easy Roll-Out Method!)

Ingredients

• 1 cup unsalted butter, room temperature
• 3/4 cup powdered sugar
• 1 tablespoon vanilla extract
• 2 cups all-purpose flour
• 1 teaspoon baking powder
• 2 cups powdered sugar, sifted, if lumpy
• 3 tablespoons milk
• 1/2 teaspoon vanilla or almond extract (optional)
• 2 + drops green food coloring