Whip the eggs and sugar (both brown and granulated) until light and fluffy (about 2-3 minutes).
In a bowl, whisk together the wet ingredients for the cake (vegetable oil, banana puree, milk and vanilla extract).
In another bowl, stir together the dry ingredients (flour, baking powder, baking soda and salt).
Add half of the dry ingredients to the egg/sugar mixture and mix on low until just incorporated.
Add the wet ingredients, again mixing on low until just combined.
Add the remaining dry ingredients, mixing until just incorporated.
Divide the batter between three lined 6" cake pans and bake at 350F for 30-35 minutes or until a toothpick inserted in the center comes out mostly clean.
Once the pans are cool enough to handle, remove the cakes from the pans, wrap in plastic wrap, and refrigerate until cold.
To make the frosting, whisk together the egg whites and granulated sugar in the bowl of a stand mixer over a pot of boiling water (a double boiler) until the sugar has dissolved and the mixture is hot.
Transfer the bowl to your stand mixer and whisk on high until the bowl has cooled to room temperature and the meringue holds stiff peaks (about 10 minutes).
Add the seeds from the vanilla bean and vanilla extract.
Cut the cold butter into cubes, switch to the paddle attachment on your stand mixer, and begin adding the butter piece by piece on medium/low speed.
Once all the butter is in, turn the mixer up to high and beat until a smooth frosting forms (5-10 minutes).
To assemble the cake, cut each layer in half.
Spread a thin layer of frosting across the top the first layer and pipe a ring of frosting around the edge.
Fill the middle with a few tablespoons of strawberry jam.
Top with the next layer of cake and repeat.
Frost the outside of the cake with the remaining frosting.
Using 15 second increments, heat the heavy cream until hot.
Add the semi-sweet chocolate chips, whisking until smooth.
Pour the ganache onto the top of the cake and drip over the sides.
Add sprinkles, dollops of frosting, cherries and banana slices to garnish.
Estimating how many bananas you'll need: For the cup of banana puree, you'll need about 4 small, ripe bananas. Add additional bananas if you plan to use them as a garnish.
Working ahead: The banana cakes can be made, wrapped in plastic wrap and frozen for up to 3 months. The cake layers can even be frosted frozen, but you won't want to level or divide them while frozen.
Chill your cake: A cool cake is easier to cut and handle, so chilling your cake for a short while before frosting it will help make the cake decorating process easier.
Fixing a “broken” meringue-based buttercream: Sometimes you’ll find that your buttercream looks “broken” or curdled. There are usually two culprits: Either it hasn’t been beaten long enough or the frosting is too warm (either from the butter being too warm or being added to the meringue too early). If continue to beat it doesn’t work, try putting it in the refrigerate for 30 minutes to cool, then continue beating.
Air bubble-free frosting: If your frosting has a lot of air bubbles in it, beat it on the lowest speed for 3-5 minutes to work them out.
Storage: This cake will keep in the refrigerator, uncut, for 2-3 days.
Storing a cut cake: Once your cake is cut, you’ll want to protect the exposed part. The easiest way to do this is to place a piece of plastic wrap directly onto the exposed cake.