Whole-wheat flour adds a layer of complexity to these cookies that all-purpose flour can't achieve; the wheat in the whole grain actually enhances the flavors of butter and vanilla. Unlike classic royal icing, which starts with a pound of powdered sugar, we use just 1/2 cup and thicken it with Greek yogurt. Looking for festive colors without the chemicals? Try naturally colored sparkling sugars (such as those from India Tree), which use colorants derived from plants.
How to Make It
To prepare cookies, weigh or lightly spoon flour into dry measuring cups; level with a knife. Whisk together flour, salt, and baking powder in a medium bowl. Beat butter, granulated sugar, and cream cheese in a large bowl with an electric mixer on high speed until light and fluffy, about 3 minutes. Add egg; beat until well blended. Add vanilla; beat until blended. Reduce mixer speed to low. Gradually add flour mixture to butter mixture; beat just until combined.
Flatten dough into a 6-inch disk; wrap with plastic wrap. Chill 1 hour.
Preheat oven to 350°F.
Roll dough to 1/4-inch thickness on a lightly floured surface. Cut out 32 cookies, using a 2- or 3-inch cutter, rerolling scraps as necessary. Place cookies 1 inch apart on baking sheets lined with parchment paper. Bake 12 minutes or until lightly browned around edges. Cool.
To prepare icing, whisk together powdered sugar, yogurt, and rind; drizzle over cookies. Sprinkle with sparkling sugar, if desired. Let stand on a wire rack until icing is set, about 15 minutes.