Peanut M&M Birthday Cake

My dad’s birthday was this past Friday, so I decided to incorporate his favorite chocolate candies, Peanut M&Ms, into his birthday cake. This was the first of two cakes I made this week (the other for my grandmother’s 95th birthday), so I prepared the cake ahead of time, froze it, and then assembled the cake the day of. I also made a simple syrup for the first time to keep the cake moist. I’m not sure how well it worked, but the cake tasted great, so I guess I can say it was a success!

This cake is a 4 layer chocolate cake filled with peanut butter buttercream frosting. The cake is then covered with a different recipe of peanut butter frosting, and decorated with Peanut M&Ms. I wouldn’t recommend either of the frosting recipes I used. Although they both tasted fine, they were very thick and did not stick to the cake well.

4 layer Peanut M&M Cake


  • 4 flat layers of prepared chocolate cake (any recipe or boxed cake)
  • 1/2 cup butter, softened
  • 1 cup creamy peanut butter
  • 4 cups confectioners sugar
  • 1/3 cup heavy cream
  • 1 tsp vanilla
  • pinch of salt
  • 1 carton buttercream icing (store bought)
  • 1/2 cup creamy peanut butter
  • 1 party size Peanut M&Ms bag
  • 1/2 cup sugar

Prepare frosting for filling:

  1. Mix full can of store bought with 1/2 cup peanut butter.

Prepare frosting for outside of cake:

  1. In stand mixer with the paddle attachment, whip the butter and peanut butter together until very smooth.
  2. Slowly add half the icing sugar until fully incorporated.
  3. Add half of the cream and blend.
  4. Add the remaining icing sugar until combined.
  5. Finish with the remaining cream, vanilla, and a pinch of salt, blending fully.
  6. If frosting is not desired consistency add more sugar or add more cream (or milk).

Prepare simple syrup:

  1. Mix 1/2 cup sugar with 1 cup water in a sauce pan.
  2. Bring to a boil, and allow to boil for approximately 3 minutes.
  3. Let cool.
  4. Use funnel to pour simple syrup into a spray bottle.

To assemble cake:

  1. Place small dollop of frosting on the center of the cake board to keep the cake in place.
  2. Place first layer of cake onto the cake board.
  3. Next, take a straw and poke several holes in the layer.
  4. Spritz cake several times with simple syrup, but be careful not to overdo it.
  5. Frost top of layer with peanut butter filling frosting (the store bought mixture).
  6. Next, crush some Peanut M&Ms and sprinkle over the frosted layer.
  7. Place second layer on top of the first layer, and repeat steps 3-6.
  8. Do the same for the third layer of cake as well.
  9. Lastly, place the fourth layer of cake on top of the third.
  10. Next cut a straw or support to be the height of the cake and place through the center of all four layers.
  11. Now take the peanut butter frosting you made for the outside of the cake (the recipe made from scratch) and ice the cake until covered and smooth.
  12. Decorate the cake with Peanut M&Ms however you desire.
  13. Keep the cake refrigerated, and wrap in wax paper if you would like to make sure the M&Ms are secure and will not fall out before you serve the cake!

Happy Birthday Dad!