Dark Chocolate Cinnamon Cupcakes
- Heat oven to 350 degrees. Line standard-sized muffin pan with baking-cup liners.
- Combine butter, chocolate, and cocoa in medium heatproof bowl. Set bowl over saucepan containing barely simmering water; heat mixture until butter and chocolate are melted and whisk until smooth and combined. Set aside to cool until just warm to the touch.
- Whisk flour, baking soda, cinnamon, and baking powder in small bowl to combine.
- Whisk eggs in second medium bowl to combine; add sugar, vanilla, and salt and whisk until fully incorporated. Add cooled chocolate mixture and whisk until combined. Sift about one-third of flour mixture over chocolate mixture and whisk until combined; whisk in sour cream until combined, then sift remaining flour mixture over and whisk until batter is thick.
- Divide batter evenly among muffin pan cups. Bake until skewer inserted into center of cupcakes comes out clean, 18 to 20 minutes.
- When the cupcakes have cooled, mix together a half teaspoon of cinnamon with 3 tablespoons powdered sugar. Sift a light coating of the mixture on top of the cupcakes.