"Being a big fan of Mexican hot chocolate, I just love the slight accent flavor of cinnamon in chocolate. This recipe for chocolate cake evolved with experimentation as I figured out how to achieve a light fluffy cake and infused it with a hint of coffee and cinnamon. Coffee enhances the flavor of cocoa powder, resulting in a more chocolaty cake. Cocoa powder is bitter on its own, with hints of fruit and spice that are detectable when you get a good-quality cocoa. Coffee has these same flavor elements, and a small amount of coffee in the batter will help these cocoa flavors stand out even more than they would on their own. Cinnamon adds another layer of richness that complements the underlying spice flavors in cocoa. Add a dollop of blackberry preserves in the center of the cupcakes."
Preheat oven to 350 degrees F (175 degrees C). Line a 12-cup muffin tin with paper liners.
Beat white sugar, brown sugar, and butter together in the bowl of a stand mixer until thoroughly blended and creamy. Add egg; beat well. Mix in 1 teaspoon vanilla extract.
Combine flour, 2/3 cup cocoa powder, baking powder, coffee, salt, baking soda, and cinnamon in a second bowl. Blend with a whisk until fluffy and no clumps appear. Alternate adding the flour mixture and 1 cup milk into the butter mixture, mixing until just combined. Fill muffin cups 2/3-full of batter.
Bake in the preheated oven until a toothpick inserted into the center of a cupcake comes out clean, 15 to 17 minutes. Move to a wire rack to cool completely, at least 25 minutes.
Beat butter in the bowl of the stand mixer; add confectioners' sugar, 1 cup at a time, beating until creamy. Add 2 tablespoons milk; mix until frosting is creamy. Mix in 1/2 cup cocoa powder and 1 teaspoon vanilla extract.
Fit a piping bag with a coupler and tip. Drop piping bag into a tall glass and fold edges down around the glass. Spoon frosting into the bag. Gather edges and twist together. Pipe frosting onto the cupcakes.