Makes about 18 muffins
1 3/4 cups plus 2 tablespoons whole wheat flour
2/3 cup cocoa powder
1 teaspoon baking powder
1 teaspoon baking soda
1/2 teaspoon espresso powder (optional)
1/2 teaspoon salt
1/2 cup light brown sugar, packed
1/2 cup granulated sugar
1/3 cup safflower or canola oil
2 large eggs
2 teaspoons vanilla extract
1 cup buttermilk
1/2 cup sour cream
1/2 cup fine chopped bittersweet chocolate or mini chocolate chips
1 cup halved fresh raspberries
Preheat the oven to 350F degrees. Line two muffin tins with paper liners or spray the cups with nonstick baking spray.
In a large bowl, whisk together the whole wheat flour, cocoa powder, baking powder, baking soda, espresso powder, and salt.
In the bowl of an electric mixer fitted with the paddle attachment, beat both sugars with the oil on medium speed until well combined. Add the eggs, one at a time, beating well after each addition. Beat in the vanilla extract.
On low speed, add the flour mixture, alternating with the buttermilk, in two additions each. Increase the speed to medium and beat until smooth. Add the sour cream, beating until fully incorporated. Stir in the chopped chocolate and carefully fold in the raspberries (try to avoid breaking them up too much!)
Using an ice cream scoop or a spoon, divide the batter among the prepared muffin cups, filling each about 2/3 full. Bake for 17-19 minutes, until the tops of the muffins spring back when lightly touched and a toothpick inserted into the center of a muffin emerges clean.
Allow the muffins to rest in the pans for 5 minutes, then transfer them to a wire rack to cool completely.