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Peanut Butter Marshmallow Cupcakes

Pillowy vanilla cupcakes hide a gooey marshmallow center and wear a billowy peanut butter–marshmallow swirl crowned with salty crushed peanuts. A nostalgic bake that balances sweet, nutty, and fluffy in every bite.
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Prep Time: 30 minutes
Cook Time: 18 minutes
Total Time: 48 minutes
Servings: 20

Ingredients
 

Cupcakes

  • 1 3/4 cups granulated sugar
  • 1/2 cup vegetable oil
  • 3 large eggs, at room temperature
  • 2/3 cup plain Greek yogurt
  • 2 teaspoons pure vanilla extract
  • 2 1/4 cups all-purpose flour
  • 2 3/4 teaspoons baking powder
  • 3/4 teaspoon fine sea salt
  • 1 cup milk, warmed
  • 1 teaspoon apple cider vinegar stir into the warm milk

Filling

  • 1 1/2 jars marshmallow creme (7-ounce jars)

Peanut Butter Swirl Frosting

  • 1 1/4 cups unsalted butter, room temperature
  • 3/4 cup creamy peanut butter
  • 4 1/2 cups powdered sugar, sifted
  • 3–4 tablespoons milk as needed for consistency
  • 1 teaspoon pure vanilla extract
  • 1 tablespoon honey
  • 1/2 cup marshmallow creme for marbling the frosting

Finish

  • 1 3/4 cups salted roasted peanuts, finely chopped
  • pinch flaky sea salt (optional)

Instructions

Preparation Steps

  • Heat the oven to 350°F. Line two standard muffin pans with 20 paper liners. Spread the peanuts on a sheet pan and toast for 5–6 minutes until fragrant, then cool and finely chop.
  • Make the frosting first so it can set: In a stand mixer with the paddle, beat the butter on medium speed until creamy, about 2 minutes. Beat in the peanut butter for 1 minute until completely smooth.
  • Add the powdered sugar in three additions, alternating with the milk and vanilla, mixing on low just until incorporated after each addition. Beat in the honey, then increase speed to medium-high and whip for 1–2 minutes until light. Fold in 1/2 cup marshmallow creme just until streaky to create a swirl. Transfer to a piping bag and refrigerate 20 minutes to firm slightly.
  • For the cupcakes, whisk the flour, baking powder, and salt in a bowl. In a separate large bowl, whisk the sugar, oil, and eggs vigorously for 2–3 minutes until paler and slightly thick. Whisk in the yogurt and vanilla.
  • Stir the vinegar into the warm milk. Add the dry ingredients to the egg mixture in two additions, alternating with the milk mixture, beginning and ending with dry. Fold just until the flour disappears, then let the batter rest 5 minutes to hydrate.
  • Portion the batter into liners, filling each about 2/3 full. Bake 16–18 minutes, rotating pans halfway, until the tops spring back and a toothpick comes out with a few moist crumbs. Cool in the pan 5 minutes, then transfer to a rack to cool completely.
  • Fill the cupcakes: Use a small paring knife to cut a 3/4-inch-wide, 1-inch-deep cone from the center of each cupcake. Spoon or pipe marshmallow creme into each cavity, then trim and replace the cake cap. Tip: Lightly oil your spoon or piping tip to keep marshmallow creme from sticking.
  • Frost and finish: Pipe a tall swirl of the chilled peanut butter–marshmallow frosting on each cupcake. Roll the sides of the frosting in the chopped peanuts and finish with a tiny pinch of flaky salt, if using.

Notes

For the neatest peanut coating, keep the frosted cupcakes slightly chilled for 5–10 minutes before rolling in peanuts. Store covered at cool room temperature for 1 day or refrigerate up to 3 days; bring to room temp before serving for the softest crumb.
This recipe is an original creation inspired by classic Peanut Butter Marshmallow Cupcakes flavors. All ingredient ratios and instructions are independently developed.