Hostess Cupcake Cake

From a whole lot of different sources, all mashed up.

Cake:
I used this cake recipe, but doubled it and baked them in 2 8-inch round pans. I cooked them at 325 for probably 35-40 min, to keep the tops flatter, a tip I read somewhere.

Frosting:
I used a marshmallow frosting recipe from Smitten Kitchen for the cream center, but I didn't love it. Next time I am going to try this one from Martha Stewart-
4 large egg whites
1 cup sugar
1/4 tsp cream of tartar
1 tsp vanilla

1. Place egg whites, sugar, and cream of tartar in the heatproof bowl of an electric mixer. Set over a saucepan with simmering water. Whisk constantly until sugar is dissolved and whites are warm to the touch, 3 to 4 minutes.
2. Transfer bowl to electric mixer fitted with the whisk attachment, and beat, starting on low speed, gradually increasing to high, until stiff, glossy peaks form, 5 to 7 minutes. Add vanilla, and mix until combined. Use immediately.

Method:
Freeze cakes for at least an hour. Flatten the top of one cake layer. Halve that layer horizontally into two thin layers. Place the first one on a cake plate. Take the second cake and cut a large hole out of the center, about 6-inches across — you won’t be using this. As carefully as possible, place this on top of the halved cake layer on the stand. Fill the entire cut-out area with frosting, leaving a half cup aside if you wish to pipe the signature loops or a message across the top. Lay the second halved layer on top of this, sealing the filling in. Spread the ganache coating over top and sides of cake. Once ganache is firm and chilled (the fridge does a great job of this, quickly), you can decorate it with a piping bag or a makeshift one, a sandwich bag with the corner snipped off.

Notes from Jill's Kitchen:
I need to cut the center hole bigger. I need to use buttercream as a crumb coat. Ganache needs to be thinner.