These cupcakes have a triple dose of coffee flavor in the cake, frosting and the doughnut glaze!Please note the frosting uses salted butter, to add mild salty-sweet flavor to the buttercream. Espresso powder can be found in the coffee aisle at the grocery store, and sometimes in the baking aisle. I use DeLallo brand most often. However, Medaglia D’oro and other high quality freeze-dried instant coffee can be used in place of espresso powder. For example, Starbucks VIA instant coffee has bold coffee flavor, is micro-ground, and dissolves easily.
Preheat oven to 350°F. Line 20 cupcake cavities with paper liners.
Combine 1/4 cup hot water and 2 tablespoons espresso powder (or instant coffee) in a small bowl; stir to dissolve.
Sift together the flour, baking soda, and sea salt. In the bowl of an electric mixer, combine the sugar, brown sugar and butter. Add the dissolved coffee mixture. Beat well on medium speed until well combined, 3 minutes. Add vanilla extract. Beat in eggs one at a time. Scrape down the bowl as needed and mix again.
Add 1/3 of the flour mixture to the bowl and beat until just combined. Beat in half of the buttermilk. Alternate the remaining flour and buttermilk, ending with the flour. Mix the last flour in until just combined. Scrape down the bowl and fold to make sure all the ingredients are well incorporated.
Use a trigger ice cream scoop (1/4 cup) or a 1/4 cup measure to portion batter into each cupcake liner, filling each about 2/3 full. Bake for 17-20 minutes, or until the cakes bounce back when pressed in their centers, or when a toothpick tester comes out completely clean.
Transfer the baked cupcakes to a wire rack to cool completely.
Salted coffee buttercream
In a small heavy saucepan set over medium heat, dissolve the sugar in the water. Bring the mixture to a boil, stirring constantly. Continue to cook until it registers 240°F on a candy thermometer.
Meanwhile, in the bowl of a stand mixer with the whisk attachment beat the eggs until they are thick and pale, about 5 minutes on medium high speed. While mixer is running, add the sugar syrup in a thin stream, carefully tempering the syrup into the eggs without cooking them. Beat until the mixing bowl is cool.
Change to the paddle attachment and add the softened butter, 1 tablespoon at a time. The mixture will deflate and look runny, then curdled. Keep adding butter and mixing. This buttercream goes through several ugly stages before it reaches fluffy consistency. When all the butter is added, add the espresso mixture. Beat on high speed until light and fluffy.
Transfer the frosting to a piping bag fitted with a large closed star tip. Pipe the frosting onto the cooled cupcakes in a large single swirl.
Doughnut batter
Preheat oven to 425°F. Spray a mini donut pan with nonstick cooking spray.
In large mixing bowl, sift together all-purpose flour, cocoa, sugar, baking powder and salt. Add buttermilk, eggs, vanilla, and butter and beat until just combined. Transfer the batter to a disposable piping bag and fill each donut cavity approximately 1/2 full. Don’t be tempted to overfill the cavities, too much batter will make these doughnuts too tall and they won’t have a hole.
Bake 5-8 minutes or until the top of the donuts spring back when touched. Let cool in pan for 2 minutes before removing. Cool completely. Wash pan, re-grease, and bake remaining batter. (Yields about 2 1/2 dozen mini doughnuts.)
Doughnut glaze
In small bowl, mix together the hot milk and instant espresso powder until dissolved.
Stir together sugar and espresso mixture until the sugar is completely dissolved. The glaze should be thick and almost opaque. Add more milk drops at a time to thin, if needed. Dip the rounded sides of the doughnuts into the glaze, about five doughnuts at a time. Wait 10 seconds then sprinkle on the nonpareils. Keep working in batches of 5 donuts until they’re all glazed and sprinkled.
Allow the doughnuts to stand until the glaze sets, about 15 minutes. Top each frosted cupcake with a single mini doughnut.
Store airtight at room temperature for 3-4 days, or they’ll keep for up to a week if refrigerated. Bring chilled cupcakes to room temperature before serving.
Notes
Flour: Use the spoon and sweep method for measuring flour if you don't have a scale. Spoon the flour into the measuring cups then sweep it level with the back of a butter knife. Don't forget to sift! Sifting is important to create a light texture. Optimal temp for ingredients: Bring the ingredients to room temperature before mixing them together. In my workshop room temperature ranges from 68-70F. Doughnut toppers: If you don't have a mini doughnut pan, and don't want to buy one, you could bake the chocolate doughnut batter in a mini cupcake tin instead. (Mini cupcake on top of the big cupcake - cute!) Spray the cavities with flour-based baking spray and bake until done, about 6 minutes. Cover the tops with the doughnut glaze and add nonpareils.