Preheat your oven to 350 degrees Fahrenheit and butter and flour a Bundt cake pan.
In a large bowl whisk together the flour, baking powder, baking soda, salt, nutmeg, and ginger. Set aside.
Next, add the butter vegetable oil and brown sugar into another bowl and beat until light and fluffy.
Then, add in the eggs and egg yolk and mix into the oil and sugar mixture.
Add the vanilla and mashed banana and mix until combined.
Next, add the dry ingredients and buttermilk and mix in on low speed until combined. Be sure not to over mix.
Pour the cake batter into your prepared Bundt cake pan and bake in the oven for 50-60 minutes until a toothpick comes out clean.
Remove the cake from the oven and allow it to cool for 5-10 minutes before gently turning it over onto a wire rack to cool.
While the cake is cooling, prepare the buttercream frosting. In a bowl beat the butter, cream cheese, vanilla, salt and 4 cups of powdered sugar until you reach a smooth consistency. If needed, you can add additional powdered sugar to reach your desired consistency.
Finally, frost the top of the cake and top with crushed vanilla wafers then serve and enjoy!
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Notes
You can store this Banana Cream Cake in an airtight container in your fridge for 3-4 days. To serve allow the cake to come to room temperature.If you want to freeze this cake do so before you add the frosting. You can store it for up to 1 month. If the cake already has the frosting on it I do not recommend freezing it because the textures will not hold up well.