Instructions

• Preheat oven to 375°F (190°C) and line a 12-count muffin pan with cupcake/muffin liners. Set aside.
• In a large bowl, whisk together 2 cups all-purpose flour, 1 teaspoon baking soda, and 1/2 teaspoon salt. Set aside.
• Place 4 ounces semi-sweet chocolate chips (or chopped) and 1/2 cup unsalted butter in a microwave-safe bowl and heat in 20–30 second intervals, stirring between intervals, until melted and smooth; or melt together in a heatproof bowl set over simmering water. Stir until smooth and let cool about 5 minutes.
• To the cooled chocolate-butter mixture, add 1 cup sugar and 1/4 cup cocoa powder. Using an electric mixer on medium-low speed, beat in 2 eggs, 2 teaspoons vanilla extract, and 1/4 cup sour cream until well combined, scraping the bowl as needed.
• Reduce mixer speed to low and gradually add the flour mixture from step 2, mixing until just combined and no large streaks of flour remain. Do not overmix.
• Gently fold in 1 cup of the 1 1/2 cups dark chocolate chips, reserving the remaining 1/2 cup for topping.
• Divide the batter evenly among the 12 prepared liners, filling each about three-quarters full.
• Bake for 20 minutes, or until a toothpick inserted into the center of a muffin comes out mostly clean (a few moist crumbs are okay).
• Remove the muffins from the oven and immediately sprinkle the reserved 1/2 cup dark chocolate chips on top of the hot muffins, pressing lightly so the chips adhere.
• Let the muffins cool in the pan for about 5 minutes, then transfer them to a wire rack to cool further before serving.