Preparation Steps

• Preheat oven to 425 degrees F and spray two 12-cup muffin tins with baking spray or line with cupcake liners.
• Combine flour, cocoa powder, baking powder, baking soda, and salt together in a medium bowl. Stir until well mixed and set aside.
• Whisk together eggs and sugar in a large bowl until smooth.
• Add oil, sour cream, milk, and vanilla to egg mixture and whisk until smooth.
• Pour the dry ingredients into the wet ingredients and stir carefully to combine until no dry patches remain.
• Scoop 1.5 tablespoons of batter into the bottom of 22 muffin cups in the prepared pans.
• Add 1 heaping teaspoon of Nutella on top of the batter in each cup.
• Top Nutella with another 1.5 tablespoons of batter to cover. Sprinkle with decorator's sugar if desired.
• Bake for 5 minutes at 425 degrees F, then reduce oven temperature to 350 degrees F and bake for an additional 10-13 minutes or until a toothpick inserted comes out clean.
• Let muffins cool in the pan for 5 minutes, then transfer to a wire rack to cool completely before serving.