Frosted Sugar Cookies - Diamond Nuts

Ingredients

• 1/2 cup finely chopped Diamond of California® Walnuts
• 2 1/2 cups all-purpose flour, plus more for rolling
• 1/2 teaspoon baking powder
• 1/2 teaspoon salt
• 1 cup (2 sticks) unsalted butter, room temperature
• 2 cups granulated sugar
• 1 large egg
• 2 tbsp milk
• 1 teaspoon vanilla extract
• 1 cup prepared vanilla frosting
• assorted sprinkles and mixed chopped nuts