Using a serrated knife, cut 2 of the cookies into 2-inch pieces (6 total). On a serving plate or tray, arrange the 2 whole cookies next to each other, leaving about 2-1/2 inches in between. Arrange the smaller cookies perpendicular to the whole cookies, forming a tic-tac-toe grid, using chocolate frosting to attach the cookies together.
Using 2 desired colors paste food coloring, tint about 1/4 cup white frosting each color. Place each color in a separate resealable plastic bag. Snip a small hole in one corner of each bag. Place cupcakes in the spaces of the cookie grid. Use the frosting to pipe on "X"s and "O"s. Makes 9 servings.