Mini Chocolate Cupcakes with Swiss Meringue Buttercream

Directions

1. 1
   Preheat the oven to 350ºF, and line mini* muffin tins with mini cupcake liners.In the bowl of a stand mixer with the whisk attachment, stir together the flour, sugar, cocoa, baking powder, baking soda, cornstarch, and salt.
2. 2
   Add the buttermilk, espresso, olive oil, eggs, and vanilla extract, and mix on medium speed for about 2 minutes, until smooth (it will be liquidy).Fill each of the prepared mini muffin tins 2/3 full with batter.
3. 3
   Bake at 350ºF for 10-12 minutes, until a toothpick in the center comes out with just a few crumbs.
4. 4
   Remove the cupcakes from the pan immediately, and place on a wire rack to cool (be careful, they will be hot). Allow to cool completely before frosting.*For regular sized cupcakes, bake at 350ºF for 15-17 minutes.Melt the chocolate in a heat proof bowl in the microwave at 30 second intervals, stirring in between. Set aside to cool. If you want vanilla buttercream, skip this step.Bring a saucepan filled with 2 inches of water to a simmer.
5. 5
   Place the egg whites and sugar into a heat proof mixer bowl, and place above the water.
6. 6
   Whisk the sugar and egg whites until warm to the touch and the sugar is dissolved.
7. 7
   Place the bowl back on the mixer stand, and whisk on medium-high speed until you have stiff, glossy peaks, and the mixture is cool, about 10 minutes.Reduce speed to medium-low, and add the butter, one piece at a time, mixing until fully incorporated between each piece. If it appears curdled at this point, keep mixing until it becomes smooth again.
8. 8
   Add the vanilla extract, melted chocolate (if using), and salt, and mix until well combined.Switch to the paddle attachment and beat for about 2 minutes to remove air bubbles.Using your favorite frosting tip, pipe frosting on top of the cooled cupcakes.
9. 9
   Serve immediately. Keep leftovers in an airtight container in the refrigerator.If you’re a visual person, there’s a great step-by-step swiss meringue buttercream post at Sweetapolita.