Place cake on a large flat serving platter or tray. Using a serrated knife, make rounded cuts to remove the two corners at the top of the cake. Trim a 1-inch strip of cake from each of the long sides. Place strips on top of cake. Place the removed corners along the bottom sides of cake to make a wider base for the rocket. Spread some frosting between cut pieces of cake to hold them in place.
Tint 1/2 cup of the Creamy White Frosting red; set aside. Frost the entire cake with the remaining white frosting.
For fuel exhaust cones with flames, cut fruit leather into 1-1/2-inch-wide strips. Use scissors to fringe one edge of each strip. Roll up strips and insert into horn-shape snacks. Insert cones with flames into bottom edge of cake.
Decorate top of cake with red jelly rings, small candies, and blue sugar. Fill a heavy resealable plastic bag with red frosting; snip a small hole in one corner of the bag. Pipe a border around top edge of cake.
Creamy White Frosting
In a large mixing bowl beat shortening, vanilla, and almond extract with an electric mixer on medium speed for 30 seconds. Gradually add about half of the powdered sugar, beating well. Beat in 2 tablespoons of the milk. Gradually beat in the remaining powdered sugar and enough of the remaining milk to reach spreading consistency.