Prepare cakes for fondant covering by lightly icing with buttercream. For jelly roll pan, roll out white rolled fondant 1/8 in. thick and place 12 in. long x 10 in. wide up next to cake. Attach circle of fondant made in step 5 to bottom of bottle with icing. Carefully roll cake onto white cut fondant, continue rolling cake until completely covered with fondant. Trim excess.