Inside-Out Neapolitan Cupcakes
Servings: 18 layered cupcakes
Ingredients
For the Cupcakes:
  • 6 tablespoons 85 g unsalted butter, softened
  • 1 cup 230 g packed dark brown sugar
  • 1 teaspoon 5 ml pure vanilla extract
  • 1 large egg at room temperature
  • 1 egg yolk at room temperature
  • 3/4 cup + 2 teaspoons 115 g all-purpose flour
  • 6 tablespoons 38 g unsweetened Dutch-processed cocoa powder
  • 1/2 teaspoon 3 g baking soda
  • 1/2 teaspoon 3 g baking powder
  • 1/2 teaspoon 5 g kosher salt
  • 3/4 cup 180 ml buttermilk, at room temperature
  • 2 tablespoons 30 ml mayonnaise
For the Swiss Meringue Buttercream:
  • 5 large fresh egg whites 150 g
  • 1-1/4 cup 250 g superfine granulated sugar
  • 1-1/2 cups 340 g (3 sticks) unsalted butter, softened, cut into cubes
  • 2 teaspoons 10 ml pure vanilla extract
  • pinch of salt
Instructions
For the Cupcakes:
  1. Preheat oven to 350° F. Butter and flour standard cupcake pans as you would for muffins, tapping out the excess.
  2. In a stand mixer fitted with the paddle attachment, beat the butter, brown sugar, and vanilla on medium-high speed until lighter in color and slightly increased in volume, about 5 minutes. Lower the speed to medium and add the eggs, one at a time, mixing until each is fully incorporated before adding the next.
  3. Sift the flour, cocoa powder, baking soda and baking powder into a medium bowl. Add the salt to the dry ingredients after sifting, and whisk dry ingredients.
  4. Alternate dry ingredients and buttermilk into creamed mixture, beginning and ending with dry ingredients. Mix until just incorporated, or finish by hand gently.
  5. Fold mayonnaise into batter with a whisk, until just blended.
  6. Fill cupcake pans 2/3 each (I like to use a 1.5 oz cookie scoop) and bake for approximately 17 minutes, or until a skewer inserted into center of cupcakes comes out just barely clean (a few crumbs). This works well for moist chocolate cake (not vanilla).
  7. Let cupcakes cool on wire rack for 10 minutes, then gently remove from pan and continue to cool on a wire rack. Let cool completely.
For the Swiss Meringue Buttercream:
  1. Wipe the bowl of an electric mixer with paper towel and lemon juice, to remove any trace of grease. Add egg whites and sugar, and simmer over a pot of water (not boiling), whisking constantly but gently, until temperature reaches 160°F, or if you don't have a candy thermometer, until the sugar has completely dissolved and the egg whites are hot.
  2. Place bowl back on mixer and fit with whisk attachment. Whip until the meringue is thick, glossy, and the bottom of the bowl feels neutral to the touch (this can take up to 10 minutes, or longer). Switch over to paddle attachment and, with mixer on low speed, add softened butter in chunks until incorporated, and mix until it has reached a silky smooth texture (if curdles, keep mixing and it will come back to smooth).
  3. Add vanilla and salt, continuing to beat on low speed until well combined.
  4. You can also add a wide variety of flavourings, extracts, and more, but always add the vanilla first, as it brings out the true taste of the other flavours.
Assembly of the Inside-Out Neapolitan Cupcakes:
  1. Divide buttercream evenly into 3 bowls. Flavour 1/3 chocolate, 1/3 strawberry, and leave final 1/3 vanilla (using instructions above). Add a few drops of pink gel colour to strawberry buttercream.
  2. Using a very sharp serrated knife, slice cupcakes twice, horizontally, resulting in 3 "layers."
  3. Fill one layer of each flavour (chocolate, strawberry, and vanilla), and top with sprinkles, if desired.
  4. Best eaten at room temperature on the day they were made, but can be stored in an airtight container for up to 3 days (in refrigerator overnight).
Sweetapolita's Notes

*Keep in airtight container in refrigerator for up to one week, leaving out at room temperature when needed, re-whipping in mixer for 5 minutes.

**Can freeze for up to 6-8 weeks. To thaw, place on counter overnight, and rewhip for 5 minutes with paddle attachment in an electric mixer.

***For Chocolate Buttercream, add 150 g (3/4 cup) melted bittersweet Belgian chocolate (the best you can get--I use Callebaut) to Vanilla Swiss Meringue Buttercream and beat until incorporated.

****For Strawberry Buttercream, add strawberry puree to taste, OR a few drops of LorAnn Strawberry Flavor Oil.