Heat oven to 350°F. Grease and flour 13x9-inch pan. Beat flour, sugar, shortening, milk, 1/4 cup crème de menthe, the baking powder, salt and vanilla in large bowl with electric mixer on low speed 30 seconds, scraping bowl constantly. Beat on high speed 2 minutes, scraping bowl occasionally. Beat in egg whites on high speed 2 minutes, scraping bowl occasionally. Pour into pan.
Bake 40 to 45 minutes or until toothpick inserted in center comes out clean or until cake springs back when touched lightly in center. Cool completely.
Spread fudge topping over cake. Carefully fold 3 tablespoons crème de menthe and the food color into whipped topping; spread over cake. Store covered in refrigerator.