Creamy Chocolate De Menthe Cake

1 18 1/4 ounce package white cake mix
5 tablespoons cr�me de menthe liqueur
1 16 ounce can chocolate syrup
1 8 ounce container cool whip, thawed

Prepare cake mix according to package directions except substitute 3 tablespoons Cr�me de Menthe for 3 tablespoons water. Pour cake batter into 13 x 9 inch pan and bake according to package directions. Cover a cookie sheet with foil and spray nonstick cooking spray lightly, set aside. Remove cake pan from oven and while hot poke holes in cake with fork. Turn cake out onto prepared cookie sheet. Slowly pour chocolate syrup over the top of cake. Refrigerate. Mix whipped topping with 2 tablespoons of cr�me de menthe and spread on a cooled cake.