Lime Sugar Bars

1. Preheat oven to 350°F. Line a 15x10-inch baking pan with foil, extending foil over edges. Remove 4 tsp. zest and squeeze 5 Tbsp. juice from limes.

2. In a large bowl beat butter and shortening with a mixer on medium to high 30 seconds. Add 3 tsp. of the lime zest, the granulated sugar, baking powder, and salt. Beat until light and fluffy, scraping bowl as needed. Beat in eggs, vanilla, and 3 Tbsp. of the lime juice until combined. Beat in flour. Spread batter into prepared baking pan.

3. Bake 20 to 25 minutes or until light brown. Cool slightly in pan on a wire rack.

4. For glaze, in a small bowl stir together powdered sugar, remaining 1 tsp. lime zest, and 4 tsp. of the lime juice. If needed, stir in enough of the remaining lime juice to reach a thin glazing consistency. Spread warm uncut bars with glaze; cool. Using foil, lift out uncut bars. Cut into bars.

Royal Icing

1. In a large mixing bowl stir together the powdered sugar, meringue powder, and cream of tartar. Add the water and vanilla. Beat with an electric mixer on low speed until combined; beat on high speed for 7 to 10 minutes or until icing is very stiff. If not using immediately, cover bowl with a damp paper towel; cover with plastic wrap. Chill for up to 48 hours.

To Decorate

To paint the bars, omit the lime glaze. Prepare Royal Icing (p. xx) and spread an even layer over cooled uncut bars (save remaining Royal Icing to frost desired cookies). Let stand several hours or overnight until completely set. In separate bowls mix green and red liquid food coloring with a few drops of water to dilute food coloring slightly. Using clean new artist paintbrushes of different widths, paint plaid patterns on cookies. Let stand until set.

*Tip

Meringue powder is a mixture of pasteurized dried egg whites, sugar, and edible gums. Look for it in the baking aisle of your supermarket or at a specialty food store.