Chocolate Cupcakes with Fluffy Vanilla Buttercream stuffed with Marshmallow

I LOVE the combination of rich chocolate and marshmallow together….

Chocolate Cupcake Stuffed with Marshmallow (@wendykou)

…The moist chocolate cake, with the fluffy marshmallow center and light buttercream make this just perfect in every way…

Chocolate Cupcake Stuffed with Marshmallow (@wendykou)

One of my favorite things to do with cupcakes is to stuff them… I love that surprise element, so whether it be marshmallow (in this case), chocolate, Nutella, salted caramel, or sprinkles (as I did with these cupcakes), it adds another element to the cupcake that just makes it that much better. I also love decorating my cupcakes with rosettes because it lends itself for the perfect balance of cake and cream AND the rosettes are pretty. When I go for bakery cupcakes, I often find myself scrapping off the excess buttercream since it is almost equal parts cake and buttercream. So in this post, I tried to take more images on rosette decorating, so you can create them as well!

Chocolate Cupcake Stuffed with Marshmallow (@wendykou)


For Chocolate Cupcakes (makes 12 cupcakes):

  • 3/4 cup plus 2 tablespoon cake flour
  • 1 cup granulated white sugar
  • 1/3 cup Valrhona cocoa powder (suuuper important for the flavor of the cake…personally, this could make or break your cake, so make sure you get some high quality cocoa powder)
  • 1 teaspoon baking soda
  • 1/2 teaspoon baking powder
  • 1/4 teaspoon sea salt
  • 1/2 cup buttermilk, at room temperature
  • 1/2 cup hot espresso (I use King Arthur espresso powder)
  • 1/4 cup avocado oil
  • 1 egg, at room temperature, lightly beaten
  • 1/2 tablespoon pure vanilla extract

For Filling:

  • 1 1/2 to 2 cups marshmallow fluff (this is dependent on how much filling you want, I’ll show you two options!!)

For Fluffy Vanilla Buttercream:

  • 2 sticks unsalted butter, softened (warmer than room temperature)
  • 290 grams confectioner’s sugar, sifted
  • 1/3 cup heavy whipping cream (heavy cream works too)
  • 1/2 tablespoon pure vanilla extract
  • Pinch of salt
  • For the pink buttercream color, add 1-2 drops of red gel food coloring.

Chocolate Cupcake Stuffed with Marshmallow (@wendykou)


For Chocolate Cupcakes:

  • Preheat oven to 350F degrees and line cupcake tin with liners.
  • In the bowl of electric mixer, sift together the cake flour, sugar, cocoa powder, baking soda, baking powder and salt.
  • In a separate bowl, use a whisk to combine together the buttermilk (if you do not have buttermilk, the substitute solution always works (combine 1/2 cup whole milk at room temperature plus 1/2 tablespoon of vinegar or lemon, stir together and allow to sit for about 5 minutes. It may start to curdle, but your cupcakes will still turn out great!!), coffee, avocado oil, egg and vanilla.
  • Using a paddle attachment to mixer, on low speed, slowly pour the liquid ingredients into the dry ingredients in mixing bowl.
  • Once combined together, turn up the mixer speed to medium and allow to mix for about 2 minutes (get your timer out and time it… over mixing can cause your cupcakes to come out hard and gross!). I usually stop the mixer towards the end of the 2 minutes and use a spatula to scrap the sides and allow the mixer to continue for the remaining time.
  • Fill cupcake tins to about 2/3 full (I used a 1/3 cup measuring cup to help scoop the batter into the liners).
  • Bake for 15-18 minutes and use toothpick to test (ensure the toothpick comes out clean!). I recommend checking on the cupcakes at 15 minutes with the oven light to see if the center of the cupcake still has a soft center (looks like uncooked cake batter) or is baked. If the center is baked, use the toothpick test. If the center is still soft, stand right there and wait a minute or two (it bakes quickly!)
  • After pulling the cupcakes out of the oven, allow it to cool for about 5 minutes before moving them from the cupcake tins to a wire cooling rack.

For Fluffy Espresso Buttercream:

  • With paddle attachment on standing mixer, combine unsalted butter and confectioner’s sugar on low speed (KitchenAid mixer speed 2) for approximately two minutes.
  • Add pure vanilla extract and continue to mix for another two minutes.
  • Add heavy whipping cream, pinch of salt, food gel coloring and increase mixer speed to medium-high (KitchenAid mixer speed 6) for another two minutes. If you would like to darker pink color, add another drop to the buttercream.
  • Stop the mixer and scrap down the sides of the bowl and mix on high (KitchenAid speed 8) for a few seconds.
  • Ready to be used immediately or can be stored in air tight container at room temperature for up to three days (The buttercream can be stored in refrigerator, but will take time to reach room temperature before it can be used).


  • Use a round pipping tip to puncture a hole and remove some of the central part of the cupcake. Here you have two options, which will also determine how much filling you need.

Chocolate Cupcake Stuffed with Marshmallow (@wendykou)    Chocolate Cupcake Stuffed with Marshmallow (@wendykou)

You can use either end of the tip (the narrow end or wide opening). The only difference is how much marshmallow filling you will get into the cupcake. If you’re a marshmallow fanatic, like me… then definitely use the wide opening downwards. I bought the large tip from Williams-Sonoma, so it’s not a branded tip with a reference number to it, but for your reference, the base (wide end of the opening) is 3.5 cm and the opening of the tip (narrow end) is 1.7 cm.

Note: if you’re filling the cupcake with salted caramel or less viscose than marshmallow, I suggest using a bismarck tip, which has a long narrow tube to essentially inject the filling into the cupcake. In this case, I would not remove any cake from the center, just directly fill the center of the cupcake.

Chocolate Cupcake Stuffed with Marshmallow (@wendykou)

Sometimes the center of the cake does not come out easily and in that case, I’ll use a pair of chopsticks to pull out the cake.

  • Use a spatula or spoon to scoop the marshmallow fluff into pipping bag fitted with a round tip (I used a Wilton 12).

Chocolate Cupcake Stuffed with Marshmallow (@wendykou)

Pipe some awesome marshmallow goodness into that cupcake.

Chocolate Cupcake Stuffed with Marshmallow (@wendykou)

Chocolate Cupcake Stuffed with Marshmallow (@wendykou)

Chocolate Cupcake Stuffed with Marshmallow (@wendykou)

I filled some with sprinkles too!!

Chocolate Cupcake Stuffed with Marshmallow (@wendykou)

Use a closed star pipping tip to create the rosettes. The rosettes look so fancy, yet they are sooooo easy!! Start with the pipping tip in the center of the cupcake.

Chocolate Cupcake Stuffed with Marshmallow (@wendykou)

As you slowly pipe out the butter cream, move the tip in a circular motion outwards. With just a few tries, you’ll be an expert at pipping roses.

If your rosette doesn’t look right, just take a butter knife and gently scrap the buttercream off and you can always add it back to the pipping bag to re-pipe!

Practice makes perfect!

After you’re done…don’t eat just yet!! Set the cupcakes together, take a picture and share it with me!! I’d love to see your creation!


**Chocolate cupcake recipe adapted from Sweetapolita.



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