In a bowl, whisk together flour, baking powder, and salt. In a separate large bowl, cream butter and sugar until light and fluffy. Beat in egg and vanilla. Gradually add dry ingredients and mix until combined. Divide dough into three equal parts.

Color one portion of dough with yellow gel icing color, another with orange gel icing color, and leave the third plain for white base.

Roll each colored dough into a log about 12 inches long. Stack the logs side by side, press gently together, and roll into a single log to create a striped effect. Wrap in plastic and freeze for 15 minutes.

Preheat oven to 350°F. Slice the chilled log into 1/4-inch thick cookies and place on a baking sheet. Bake for 12-15 minutes until edges are golden.

Cool cookies on a wire rack. Decorate with additional icing if desired, and serve.