Chocolate Sour Cream Bundt Cake

From Cook's Illustrated. Recipe is here.

Notes are from the Cook's Illustrated website:

Natural (or regular) cocoa gives the cake a fuller, more assertive chocolate flavor than does Dutch-processed cocoa. In addition, Dutch-processed cocoa will result in a compromised rise. The cake can be served with just a dusting of confectioners' sugar but is easily made more impressive with Tangy Whipped Cream and Lightly Sweetened Raspberries (recipes follow). The cake can be made a day in advance; wrap the cooled cake in plastic and store it at room temperature. Dust with confectioners' sugar just before serving.

Other notes:
1. Eggs, butter, and sour cream are to be at room temperature.
2. Extra time is needed to allow initial cocoa mixture to return to room temperature.

Serves 12 to 14.

INGREDIENTS

Cake Release for pan
1 Tbl butter, melted
1 Tbl cocoa

The Cake
3/4 cup natural cocoa (2 1/4 ounces)
6 ounces bittersweet chocolate , chopped
1 tsp instant espresso powder (optional)
3/4 cup water (boiling)
1 cup sour cream , room temperature
1-3/4 cups unbleached all-purpose flour (8 3/4 ounces)
1 tsp table salt
1 tsp baking soda
1-1/2 sticks of unsalted butter, room temperature (12 Tbls)
2 cups packed light brown sugar (14 ounces)
1 Tbl vanilla extract

5 large eggs, room temperature

confectioners' sugar for dusting

PREPARATION

For the pan, which can be done while cocoa mixture, below, is cooling in Step 5.

1. Stir together butter and cocoa in small bowl until paste forms.

2. Using a pastry brush, coat all interior surfaces of standard 12-cup Bundt pan, see illustration below. (If mixture becomes too thick to brush on, microwave it for 10 to 20 seconds, or until warm and softened.)

For the cake

Adjust oven rack to lower-middle position; heat oven to 350 degrees.

3. Whisk flour, salt, and baking soda in second bowl to combine. Set aside.

4. Combine cocoa, chocolate, and espresso powder (if using) in medium heatproof bowl.

5. Pour boiling water over cocoa mixture and whisk until smooth. Cool to room temperature.

6. When cocoa mixture is room temperature, whisk in sour cream.

7. In standing mixer fitted with flat beater, beat butter, sugar, and vanilla on medium-high speed until pale and fluffy, about 3 minutes.

8. Reduce speed to medium and add eggs one at a time, mixing about 30 seconds after each addition and scraping down bowl with rubber spatula after first 2 additions.

9. Reduce to medium-low speed (batter may appear separated); add about 1/3 of flour mixture and half of chocolate/sour cream mixture and mix until just incorporated, about 20 seconds.

10. Scrape bowl and repeat using half of remaining flour mixture and all of remaining chocolate mixture.

11. Add remaining flour mixture and beat until just incorporated, about 10 seconds.

12. Scrape bowl and mix on medium-low until batter is thoroughly combined, about 30 seconds.

13. Pour batter into prepared Bundt pan, being careful not to pour batter on sides of pan.

14. Bake until wooden skewer inserted into center comes out with few crumbs attached, 45 to 50 minutes.

15. Cool in pan 10 minutes, then invert cake onto parchment-lined wire rack; cool to room temperature, about 3 hours.

16. Dust with confectioners' sugar, transfer to serving platter, and cut into wedges; serve with Tangy Whipped Cream and raspberries, if desired.