Here is the Birthday cake that Al and Ash made for the birthdays. They started with a Betty Crocker Fudge Marble Cake mix. They made it according to directions PLUS added 1/2 cup flour, 1/2 cup sugar, 1 additional egg and 1 tsp baking powder. They otherwise followed the directions on the box, baking it as suggested for 9" round pans.
The did a beautiful job marbling the chocolate batter into the yellow cake, but could easily modify the recipe to include no chocolate (for those non-chocolate lovers out there Cassie and Jessie).
The frosting was a chocolate marshmallow buttercream, and the filling was a simple vanilla buttercream.
Chocolate Marshmallow Buttercream
2/3 cup cocoa powder
1/3 cup boiling water
1 stick butter softened
2 tsp vanilla
1/ tsp salt
4-5 cups powdered sugar (or more depending on humidity)
1/2 cup marshmallow fluff
Pour the boiling water over the cocoa powder and stir to make a paste. Using an electric mixer, add butter, salt and vanilla. Beat in powdered sugar and fluff. You may need more powdered sugar or more water depending on the humidity. The frosting should be thick and delicious.
4 T butter, softened
1 tsp vanilla extract
4 cups powdered sugar
1 - 2 T milk
Beat butter, extract and 2 cups powdered sugar. Add 2 T milk and continue beating. Add more sugar, enough to make frosting thick.