Line 2 large muffin tins with cupcake liners. Preheat the oven to 350°F and place oven racks in the upper-middle and lower-middle positions. Lightly spray each liner with baking spray (this is optional, but it will help prevent the cupcakes from sticking to the liners).
In a medium-sized bowl, whisk together the flour, cocoa powder, baking powder, and salt. In a small bowl or liquid measuring cup combine the buttermilk and vanilla extract.
In a stand mixer with the paddle attachment, cream the butter and sugar together on medium speed for several minutes. Scrape down the sides and the paddle. Add the eggs on low speed, one at a time, scraping down the sides all the way to the bottom of the bowl, until they’re completely incorporated.
On medium-low speed, alternate between adding the dry and wet ingredients over the course of a minute, until the ingredients are just mixed evenly. Give the bowl one more scrape, all the way to the bottom, to make sure there are no patches of flour or butter. This step is very important. Turn the mixer back on medium speed for another 30 seconds to bring some structure to the batter.
Evenly distribute the batter between the cupcake liners. They should each be around 3/4 of the way full. Bake for 22 minutes, or until the center of one of the cupcakes comes out clean with a toothpick. Allow to cool completely before removing from the pan.
Prepare the buttercream:
Add sugar and water to a medium sized sauce pot. Cover and turn the heat to high. Once the liquid begins to simmer and steam has developed, remove the cover (this helps prevent crystallization). Using a candy thermometer, cook the sugar to the soft boil stage, 235-240 degrees F.
While the sugar is cooking, whisk the egg whites on high speed in a stand mixer with the whisk attachment until a soft peak has formed.
Turn the mixer speed down to medium low and very slowly pour the syrup down the side of the bowl into the egg whites. This will make the whites safe to consume. Don’t pour the hot syrup directly into the meringue or you’ll get scrambled eggs.
Once the syrup is completely incorporated, turn the speed to high and allow the meringue to continue to form a stiff peak while cooling down. Mix on high until the meringue has reached room temperature. To speed up this 15-20 minute process, ice packs can be placed around the bowl.
While the meringue is cooling, puree the cherries in a blender or food processor. If the cherries are still cold, microwave them briefly until they’re room temperature or lukewarm. Buttercream has a tendency to break when cold ingredients are added.
When the meringue reaches room temperature, it’s time to add the butter. VERY SLOWLY, with the mixer on medium low speed, begin to add the pieces of chopped butter, allowing each piece of butter to incorporate before adding the next. It’s natural for the meringue to deflate slightly during this process. See notes on how to deal with a broken buttercream if you run into issues during this step.
Once the butter is incorporated, add the orange juice. Next, begin adding the cherry puree, 2 tablespoons at a time, until it is all incorporated.
To pipe the cupcakes, place the buttercream in a pastry bag with a decorative tip of choice. Pipe the buttercream evenly onto each cupcake and serve.
Notes
I've tested variations of these cupcakes with heavy cream, half & half and buttermilk. Each way will work so I recommend using what you have as opposed to making a special trip to the store.If your buttercream breaks (it will look like cottage cheese), don't panic. This has happened to me so many times and it's actually very easy to fix. It just means that the butter is separating from the egg whites and needs to be brought back together. The best way to fix broken buttercream is to scoop 2-3 tablespoons of it into a small ramekin and microwave it for about 7-10 seconds. With the stand mixer running on high speed, add it back into the buttercream. Keep repeating this process until the buttercream comes back together. Works for me every time. Check out my post on buttercream basics for more info!