For the inside of the stars cake, I used a white cake box, replaced the oil with melted butter and added 1 box of white chocolate pudding and 1 cup of sour cream. Then I separated the batter so I can change the colors. So the inside of the cake was rainbow and the consistency looked like play dough, but it tasted so good.
I used a simple butter cream recipe from the box of powdered sugar for the base frosting. Then I topped it with a marshmallow fondant and decorated it. Since I am a newbie at fondant, I had lots of cornstarch all over, so I used a small paint brushed and painted the stars and letters with water.