3/4cupunsalted butter1 1/2 sticks at room temperature
1teaspooninstant espresso powder(optional)
2cupsall-purpose flour spooned and leveled
2/3cupunsweetened cocoa powder
½cupbittersweet chocolate chipsplus extra for topping
1tspground canelaor cinnamon (optional)
Preheat oven to 350°F and prepare 2 muffin trays with liners; this recipe makes about 30 muffins.
Cream the butter and sugar on low with a hand mixer or stand mixer fitted with paddle attachment. After 1 minute, increase the speed to medium-high and continue beating for 2 minutes until creamy and light. Add eggs, one at a time, beating well after each addition. Add sour cream, vanilla, and espresso; mix well.
In a separate bowl, whisk the flour, cocoa, baking soda and salt; add to the creamed mixture alternately with buttermilk, beating on low after each addition. Use a spatula to fold in the chocolate chips in (scooping along the bottom especially) to incorporate everything *just until you don't see any streaks* but avoid over-mixing.
Spoon the fluffy batter into the cupcake liners only halfway (this is imperative! Only halfway!). Smooth the tops, then bang the tray hard on the counter to release any air pockets. Top with canela (if using). Bake on the middle rack until a toothpick inserted in the center comes out clean, 19-21 minutes. Straight out of the oven, top with extra chocolate chips, if desired. Cool completely, then remove.
Buttermilk: To make your own buttermilk, measure 1 tablespoon apple cider vinegar or lemon juice into a liquid measuring cup and fill to the 1 cup line with whole milk (2% works also).