A wonderfully soft and fluffy peanut butter layer cake bursting with beautiful peanut butter flavour and filled with a luscious and silky peanut butter mousse cream frosting. This cake can be paired with any of your favourite fillings and frostings to become the peanut butter cake of your dreams.

It’s funny how as an avid baker you can constantly make a cake and claim it as your favourite. It’ll be this way until the next time you create a cake that you love and suddenly that cake becomes your favourite.

I absolutely adore peanut butter and love using it in desserts. Whether baked as cookies or used as a frosting, peanut butter is delicious and very versatile. There are so many different things you can make with it but a layer cake is truly the ultimate.

This recipe uses peanut butter in both the cake and the frosting. It can be tricky to incorporate it into a cake as peanut butter can be a little high maintenance and make your cake dry and dense. Achieving that perfect soft and tender crumb requires a few simple steps and some key ingredients.

Key Ingredients

Flour: you can use cake flour in the recipe instead of all purpose or plain flour. This will make your cake softer and more delicate. Cake flour isn’t easily accessible to everyone so to achieve that same desired effect, we’re going to use a combination of all purpose flour and cornstarch.
Baking powder & baking soda: I use both raising agents; baking powder to give a nice lift to the cake and baking soda to react with the acids in the cake. The baking soda will act as a tenderizer and produce that soft crumb.
Butter & oil: I use a combination of the two; butter for that undeniable flavour and soft bite to the cake and oil to enhance the moisture. Using oil also creates a looser crumb.
Brown sugar: used for flavour and it’s reaction with the baking soda to give a soft and tender cake texture.
Whole eggs: as we are using peanut butter, whole eggs yield a nice rise to the cake and holds the crumb together.
Sour cream: this is the most important of ingredients as this guarantees that delectable, super moist crumb. Sour cream is mandatory but if you don’t have it you can use Greek yoghurt in it’s place.
Milk: used to loosen the batter as well as ensure the cake doesn’t become too heavy.

In terms of peanut butter, I use the regular commercial brands like Skippy or Jif as it works really well in both the cake and the frosting. I’ve not tried using natural peanut butter brands so I’m not sure if it will work the same way.

Peanut butter Mousse

Let’s talk frosting. My favourite frosting on anything is peanut butter frosting, I love it paired with literally any other flavour. I really wanted to have a peanut butter on peanut butter cake recipe in my repertoire so I decided to make a peanut butter buttercream frosting for this cake. I elevated my go-to frosting recipe by whipping up some cream to soft peaks and folding it into the prepared frosting.

The frosting is very easy to make as it’s just like any standard buttercream, with the addition of peanut butter. Incorporating the whipped cream into the buttercream lightens the frosting making the texture super fluffy and creamy, just like mousse. Don’t skimp on this last ingredient because the whipped frosting is magical in combination with the texture of the cake.

Tips for Success

The cake comes together using a standard creaming method. This means that you beat the butter and sugar together until the mixture is pale in colour and creamy in texture. Make sure to cream the mixture long enough as this is what gives the cake it’s structure.
Try your best not to substitute ingredients as any change can give a different result to the baked cake.
Feel free to fill and frost the cake with other flavours such as vanilla, chocolate or caramel. I highly recommend trying it with the peanut butter mousse frosting in this post as it is truly fantastic.
My ultimate tip for baking any cake is to cool the cakes on a wire rack for only 10 minutes. Then immediately store them in an airtight container to continue cooling completely. This technique locks in the moisture.

Enjoy this peanut butter layer cake and have fun paring it with different fillings and frostings!