This batter makes three 8 or 9 inch cake layers or four 7 inch layers - now I like my layers tall - so I use 3 inch tall cake pans. If you use 2 inch tall cake pans you'll have to use more layers, more like four 9 inch layers
prepare your pans with non stick spray and parchment circles (I used 4 seven inch pans)
in mixer or large bowl mix together then sugars, flour, baking powder, baking soda and salt
add the softened butter and beat - it will be sandy
in a separate bowl mix the eggs, sour cream, vanilla and peanut butter
add the wet mixture to the dry and beat
while mixing on low add the milk
pour the batter into the prepared pans
bake for 25-30 mins - until it bounces back when pressed and is just starting to pull away from the sides
let cool before starting the mousse
Peanut Butter Mousse
Beat the cream, sugar and vanilla until stiff peaks form
in another bowl beat the cream cheese and peanut butter
add the whipped cream and mix until incorporated
Assembly
level the tops (and the bottoms for a nice looking slice of cake) of the cooled cakes
wrap some cake collar acetate evenly around the cake on a cake plate or cardboard circle
add 1/3rd of the mousse, add another layer of cake and repeat (if your acetate isn't tall enough you may need to add another round, I did)
refrigerate until the mousse is set, at least 4 hours
Peanut Butter Buttercream Frosting
In a large mixer with whisks or large bowl with a hand mixer beat the egg whites, sugar and salt for 5 mins
while beating on medium add the butter 1-2 Tbsp at a time
once all the butter is mixed in add the vanilla and peanut butter and beat on medium high another 10 mins
take out 3/4th of the frosting and set aside - add 1/4 C cocoa to the remaining 1/4 of the frosting and beat until totally mixed in
Ganache
bring the cream to a boil and pour over the chocolate
let sit 5 mins then stir until smooth
let cool at room temperature while frosting the cake
Frosting
take the cake out of the fridge and unwrap the acetate
frost the top of the cake with the peanut butter frosting
then pipe around the outside of the cake alternating as much or little as you like with the chocolate peanut butter frosting
scrape around the cake smoothing the sides and creating the stripes
let the cake chill 10 mins
using a piping bag or squeeze bottle add the drips around the outside of the cake
then spread the remaining ganache on the top of the cake (without causing extra drips)
now decorate with all the peanut butter cookies and candies
Video
Notes
In the video I thought it would be fun to add mini peanut butter cups to the mousse layer in side the cake - BUT they didn't cut well and ended up ruining my cake slices so I advice NOT to do that