Have you ever heard of a Dirty Diet Coke? It’s a thing, you know!?! In case you aren’t’ familiar with the wonderful Dirty DIet Coke, it is a Diet Coke with coconut syrup and lime. I heard about it from my friends that live in Utah. Swig N’ Sweets is famous for their Dirty Diet Cokes (and their cookies are dang good too!). I love Diet Coke, and a Dirty Diet Coke is a fun way to jazz up my favorite beverage.

Coca-Cola Cake is one of our favorite desserts. Chocolate cake made with Coke – so good! I was thinking of desserts for our Memorial Day cookout and thought why not make a Dirty Diet Coke Cake!?!?! OMG! Y’all, this is SO good!!! We both ate WAY too much of this cake. Chocolate cake and Diet Coke – I can’t think of many things better in this world!

I used coconut extract in the cake. I didn’t think most people would have coconut syrup in their pantry, so I used the extract. It worked great. I used fresh lime juice and zested the limes. Perfect!!

You can make this cake a day in advance and store it in an air-tight container until you are ready to serve. I hope y’all enjoy it as much as we did!!



  • 2 cups sugar
  • 2 cups all-purpose flour
  • 1-1/2 cups small marshmallows
  • 1/2 cup butter
  • 1/2 cup vegetable oil
  • 3 Tbsp cocoa powder
  • 1 cup Diet Coke
  • 1 Tbsp coconut extract
  • 3 Tbsp lime juice
  • zest of one lime
  • 1/2 cup buttermilk
  • 1 tsp baking soda
  • 2 eggs


  • 1/2 cup butter
  • 3 Tbsp cocoa powder
  • 6 Tbsp Diet Coke
  • 1 (1-pound) box powdered sugar
  • 2 Tbsp lime juice
  • 1-1/2 tsp coconut extract


  1. Preheat oven to 350º F. Grease and flour a 9×13-inch pan. Set aside.
  2. In a large bowl, sift sugar and flour. Add marshmallows.
  3. In saucepan, mix butter, oil, cocoa, and Diet Coke. Bring to a boil and pour over dry ingredients; blend well.
  4. Dissolve baking soda in buttermilk just before adding to batter along with eggs, lime juice and coconut extract, mixing well.
  5. Pour into prepared pan and BAKE 35 to 45 minutes. Remove from oven and frost immediately.


  1. To make frosting, combine butter, cocoa and Diet Coke in a saucepan. Bring to a boil and pour over confectioners’ sugar, blending well. Add lime juice and coconut extract. Spread over hot cake.
  2. When cool, cut into squares and serve.