White Christmas: Festive Holiday Cookies

The heavenly flavor of orange with walnuts makes a merry combination in these tangy, crispy sandwiches.

Makes: about 4 dozen

Work: 45 minutes

Total: 5 hours 15 minutes

Ingredients

4 large egg whites, room temperature

4 1/4 cups sifted confectioners' sugar

4 teaspoons white vinegar

1 teaspoon orange zest

3/4 cup finely chopped walnuts

1/4 cup unsalted butter, softened

2 tablespoons orange juice

1/4 teaspoon vanilla extract

Directions

1. Heat oven to 225 degrees F. Line 2 baking sheets with parchment. Prepare a large pastry bag fitted with a 1/2-inch plain tip or coupler; set aside.

2. In the bowl of an electric mixer, whisk together egg whites and 2 1/2 cups confectioners' sugar. Place bowl over a pot filled with an inch of simmering water over medium heat. Whisk lightly for about 2 minutes, until warm to the touch and all the sugar has dissolved. Transfer bowl to mixer stand or use a hand mixer and whisk on medium-high speed for 5 minutes, until mixture has cooled and firm peaks form when you lift the whisk from the bowl. Reduce speed to medium, add vinegar and orange zest, and beat for 1 minute more. Gently fold in walnuts.

3. Transfer meringue to the prepared pastry bag and pipe 1-inch mounds 1/2 inch apart on baking sheets. Bake immediately, using two oven racks, for 30 minutes. Reduce oven to 175 degrees F. and bake 2 hours more, or until cookies feel firm to the touch. Turn off oven and leave meringues inside to dry for at least 1 1/2 hours or overnight.

4. Make buttercream by combining butter, 1 3/4 cups confectioners' sugar, orange juice, and vanilla; beat until smooth. Spread buttercream on the flat sides of half the cookies, then sandwich together.