Chocolate Sour Cream Bundt Cake

Cake Release
1 tablespoon melted butter
1 tablespoon cocoa

Cake
3/4 cup natural cocoa (Not Dutch)
6 oz bittersweet chocolate, chopped
1 teaspoon instant expresso powder (optional)
3/4 cup boiling water
1 cup sour cream, room temp
1 3/4 cups unbleached all purpose flour
1 tsp salt
1 tsp baking soda
12 tbsp unsalted butter, room temp
2 cups packed light brown sugar
1 tsp vanilla extract
5 large eggs, room temp
confectioner's sugar for dusting

For the pan
Stir together butter and cocoa in small bowl until paste forms; using a pastry brush, coat all interior surfaces of standard 12-cup bundt pan. Heat oven to 350 degrees.

For the cake
Combine cocoa, chocolate, espresso powder in medium heatproof bowl; pour boiling water over and whisk until smooth. Cool to room temp; then whisk in sour cream. Whisk flour, salt, and baking soda in a second bowl to combine.

In standing mixer fitted with flat beater, beat butter, sugar, and vanilla on medium-high speed until pale and fluffy, about 3 min. 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 3 additions. Reduce to medium-low speed(batter may appear separated); add about 1/3 flour mixture and 1/2 chocolate/sour cream mixture and mix until just incorporated, about 20 seconds. Scrape bowl and repeat using 1/2 remaining flour mixture and all of remaining chocolate mixture; add remaining flour and beat until just incorporated, about 10 seconds. Scrape bowl and mix on medium-low until batter is thoroughly combined, about 30 seconds. Pour batter into prepared bundt pan, being careful not to pur batter on sides of pan. Bake until wooden skewer inserted into center comes out with few crumbs attached, 45-50 min. Cool in pan 10 min, then invert cake onto parchment-lined wire rack; cool to room temp, about 3 hrs. Dust with powdered sugar.

Cook's Illustrated 2004