- For white icing, in a medium bowl, combine powdered sugar, corn syrup, 1 tablespoon of the milk, and vanilla. Beat with an electric mixer on low speed until combined. Stir in the remaining 1 tablespoon milk, 1 teaspoon at a time, to make an icing of drizzling consistency. Place half of the white icing in a small bowl.
- For cocoa icing, stir cocoa powder and the 1 to 1-1/2 teaspoons milk into the remaining white icing, making an icing of piping consistency.
- Place cookies on a wire rack set over a piece of waxed paper. Spoon the white icing into a decorating bag fitted with a small round tip. (Or fill a resealable plastic bag; snip off one small corner.) Pipe icing in a very thin line down the center of each cookie; pipe the outline of icing around half the border of a cookie. Let stand until outlines are slightly firm.
- Pipe the white icing into the center of the icing outline; use a toothpick to spread icing to edges. Repeat piping process with the cocoa icing on the other half of each cookie. Let stand until firm. Makes 8 to 10 cookies.
From the Test Kitchen
Lay frosted cookies in a single layer in an airtight container; cover. Store at room temperature for up to 3 days.