To me, black bottom cupcakes are basically the most perfect sweets, as it they are essentially chocolate cake with frosting (okay, filling), usually cream cheese, on the inside. I totally dig the color combo (the deep dark brown of the cake and the creamy white of the filling), the surprise factor of finding a filling in one’s tiny cake; and, you know, the fact that a black bottom cupcake is kind of reminiscent of a hostess cupcake, doesn’t hurt either. Now, the first time I developed a recipe for black bottom cupcakes, I was heavily influenced by recipes I found on Smitten Kitchen and Baked Sunday Mornings. But this go-around I wanted to shake things up a bit with a mascarpone, rather than cream cheese, filling, and an attempt at using my grandmother’s chocolate cake recipe for the “black bottom” component of my treat.
interestingly enough, at least to a recipe-development nerd like me, i found almost no mascarpone-filled black bottomed cupcakes on the internet, or in the books on my shelves, save for this, which a little sleuthing revealed is a recipe from this. and i was really, kind of flummoxed, as mascarpone seemed like such an obvious (and obviously awesome) substitute for cream cheese in a filled cupcake. but, of course, the dearth of mascarpone-filled chocolate cups was also somewhat thrilling, as it provided me with the chance to develop a somewhat “unique” sweet treat (and truth be told, my mascarpone filling was super runny and difficult to “fill” my cups with, until i froze it til scoopable. so, perhaps it was the runny-ness-factor that proved to be an obstacle to others? not sure . . . but i digress). 
As for using my grandmother’s chocolate cake recipe, it took only the tiniest bit of internet research, until, sadly but not surprisingly, I found an identical recipe to her’s (save for the vanilla — my grandmother’s called for none). Moreover, I quickly discovered that both my grandmother’s recipe and the internet source were likely just versions of something called the “Hershey special cake,” a chocolate cake recipe from this Hershey’s Cookbook. But despite this discovery, and the fact that I have no memory of ever having actually eaten my grandmother’s cake, I was committed to giving it a try (with a tweak or two, to make it my own). I amped up the amount of sugar in her recipe and changed it to dark brown, melted the butter, substituted a yolk for an egg, increased the amount of salt, and added vanilla. I kept the vinegar/baking soda combo (added to the batter, together, at the end), as we always did so at Baked, when making the red velvet cake, and the unsweetened chocolate, as well. And then I called it a day. I filled my grandma’s cake (in cupcake form) with my (frozen) mascarpone creaminess, And you know what? It was kind of a complete bust.
First, I hated the color of the cake. It was a lightish brown from the unsweetened chocolate, but without cocoa powder it lacked the rich brown color I love in a chocolate cake. Moreover, it just wasn’t chocolate-y enough in flavor. I realized cocoa powder was a must (for color and depth of flavor), and that maybe those mini chocolate chips I had imagined studded throughout my filling needed to make an appearance. With these two modifications, negligible as they might seem, my black bottomed babies were transformed. They were uber chocolate-y — might I even say fudgy? — craggly topped, with deep crevices, leading down to a tangy center laced with mini chips, and if eaten when still warm (which I HIGHLY recommend) the oozy filling and tender cake provide the most perfect coupling of both flavor, as well as texture. Can I just say, we’re talking extremely yummy, somewhat unique, black bottom cupcakes that you will love. No kidding.
Mascarpone-Filled Black Bottom Cupcakes
Ingredients
Mascarpone filling
- 8 oz mascarpone cheese
- 1 large egg
- 1/3 cup granulated sugar
- 1/4 tsp salt
- 1/2 tsp pure vanilla extract
- 1/3 cup mini chocolate chips
Chocolate cupcakes
- 1 1/2 cups cake flour sifted
- 1/2 cup dutch process cocoa powder
- 3/4 tsp salt
- 1 stick unsalted butter
- 2 ounces unsweetened chocolate
- 1 3/4 cups dark brown sugar packed
- 1 large egg
- 1 yolk
- 2 tsp pure vanilla extract
- 1 cup buttermilk room temp
- 1 tbsp vinegar
- 1 tsp baking soda
Instructions
To make the mascarpone filling
- Combine the mascarpone cheese, egg, sugar, salt, vanilla, and chocolate chips in a small bowl and whisk lightly to combine. Place in the freezer, for at least an hour, stirring every fifteen minutes or so, until scoopable.
To make the cupcakes (don't begin this step until the filling is scoopable)
- Preheat the oven to 350 degrees and line a cupcake pan with paper liners. Combine the sifted flour, cocoa powder, and salt in a medium sized bowl and whisk. Set aside. Place the butter and chocolate in a small microwave-safe bowl, and microwave on high, for 20 second intervals, stirring after each interval, until melted. Alternatively, place the butter and chocolate in a small sauce pan and melt over medium heat on the stove-top, stirring often.
- Place the warm butter/chocolate and sugar in the bowl of a stand mixer fitted with the paddle attachment and on medium speed, beat them together until combined, scraping the bowl with a rubber spatula, as needed. add the egg, then yolk, then vanilla, mixing after each addition and continuing to scrape as needed.
- On medium low speed, add the flour/cocoa powder/salt to the mixing bowl, in three additions, alternating with the buttermilk, and beginning and ending with the dry ingredients. The first addition of dry should be the largest (add more than 1/3 of the dry ingredients initially). Stop the mixer and remove the bowl when there are still streaks of flour throughout the batter. Use a rubber spatula to incorporate the streaks.
- In a small bowl, combine the vinegar and baking soda, whisking with a fork to dissolve the baking soda. Work quickly, and once the baking soda is dissolved and the mixture is furiously bubbling, add it to the batter, bubbles and all. Stir with a rubber spatula to incorporate.
- Place 1 1/2 tbsp of batter in each paper lined cup (I used a 1 1/2 tbsp ice cream scoop). Add a 1 1/2 tbsp scoop of mascarpone filling (using a small offset spatula to press the filling down into the batter, if necessary) and add a final 1 1/2 tbsp scoop of batter. Use the offset again to smooth the top layer of batter over the mascarpone (easier said than done, but do your best).
- Place the cupcakes in the oven and bake for 22 to 24 minutes, rotating after 12. Begin checking on the cupcakes at 20 minutes, sticking a cake tester into the cupcakes (avoiding the filling if possible) until the tester comes out with a few moist crumbs. The cupcakes will sink (see my pictures) so do not be alarmed.
- Place the cupcakes, still in the pan, on a wire rack and cool until you can remove them with your hands. Serve while still warm on plates with forks (they can be a bit messy at this stage — but, oh so good). The cups will keep at room temperature, covered in plastic wrap for a day or two, but are best eaten the day they are made.