Peanut Butter Cupcakes with a Marshmallow Swirl

1/4 cup butter, softened
1/2 cup creamy peanut butter
1 cup granulated sugar
2 large eggs
2 teaspoons vanilla extract
1 1/2 cups all-purpose flour
1 1/4 teaspoon baking powder
1/3 cup milk
1/2 cup peanut butter morsels
2/3 cup marshmallow fluff
Preheat oven to 350 degrees F.
Cream butter and peanut butter together in the bowl of an electric mixer until smooth and creamy. Add sugar and eggs and beat together until fluffy. Add vanilla and mix for another minute or so.
Combine dry ingredients in a bowl. Add half of the dry ingredients, mixing until just combined. Add the milk. Once mixed, add remaining dry ingredients. Fold in peanut butter morsels and marshmallow fluff.
Pour into cupcake tins and fill 2/3 of the way full. Bake for 15-18 minutes at 350. Let cool completely before frosting.
Note: since the marshmallow fluff can harden a bit, I would advise making these cupcakes the same day you eat them.

Peanut Butter Frosting
2 tablespoons butter, softened
1/4 cup creamy peanut butter
1 teaspoon vanilla extract
3/4 cup powdered sugar
1-2 teaspoons milk, if needed
Beat butter and peanut butter in the bowl of an electric mixer until creamy. Add in vanilla extract, then with the mixer on low speed, add in powdered sugar. Increase speed to medium-high and beat for 2-3 minutes until fully combined, scraping down the sides. If frosting is too thick, add in milk and beat for 1-2 minutes more. Fill a pastry bag with frosting or using a spoon, poke a hole into the cupcake and fill.

Marshmallow Buttercream Frosting
1 cup butter (2 sticks), softened
1 tablespoon vanilla extract
1 1/2 cups marshmallow fluff
3 cups of powdered sugar
Beat butter in the bowl of electric mixer until creamy. Add in fluff and beat for 2-3 minutes, then add in vanilla extract. With the mixer on low speed, add in powdered sugar 1 cup at a time until fully incorporated. Once all the sugar has been added, beat on medium-high speed for 2-3 minutes. If mixture if too runny, add a bit more sugar. If it’s too thick, add a bit of milk one tablespoon at a time. Frost cupcakes and drizzle with melted peanut butter if desired.