Heat oven to 350°F. Line large cookie sheet with foil; grease foil with shortening. In large bowl, break up cookie dough. Stir or knead in flour. With floured fingers, press dough on foil to form crust, shaping into slightly oval egg shape.
Bake 15 to 20 minutes or until deep golden brown. Cool completely, about 30 minutes.
Use foil to lift crust from pan. Carefully remove foil from crust; place crust on serving platter or tray. Spread 3/4 cup of the frosting over crust. Arrange jelly beans, marshmallows and candies over top to create fun Easter egg design, using photo as a guide.
In small microwavable bowl, microwave remaining frosting on High 10 to 15 seconds or until thin and drizzling consistency. Stir in food color to make desired color. Spoon into small resealable food-storage plastic bag; seal bag. Cut 3/8-inch tip off bottom corner of bag. Squeeze frosting on cookie pizza, creating a design. Cut into wedges or squares.