Beat butter and sugar until pale and fluffy, about 2 minutes, then mix in egg and vanilla.

Whisk flour, baking powder, and salt. Stir into the butter mixture until dough forms. Chill 30 minutes. Roll to 1/4 inch thick, cut footballs.

Bake at 350°F (175°C) for 10-12 minutes, edges barely golden. Cool on sheet 5 minutes, then transfer to rack.

Stir powdered sugar, meringue powder, and 3 tablespoons water until thick and smooth. Reserve 2 tablespoons white. Color the rest with brown gel.

Pipe brown outline on each cookie, flood the center, then use white icing to pipe center line and three short lace lines while brown is wet.

Let icing dry about 30 minutes until firm, then serve.