Ingredients:
4 ounces unsweetened chocolate, chopped
1/4 cup Dutch-processed cocoa powder
1 1/4 cups boiling water
3/4 cup all-purpose flour
3/4 cup cake flour
1 teaspoon baking soda
1/4 teaspoon salt
8 ounces unsalted butter, softened
1 1/2 cups packed dark brown sugar
3 large eggs, room temperature
1/2 cup sour cream
1 teaspoon vanilla extract
Directions:
Adjust oven rack to upper- and lower-middle positions; heat oven to 350 degrees.
Grease three 8-inch pans, line bottom of each pan with parchment paper round, grease agin and flour.
Combine chocolate and cocoa in medium bowl; pour boiling water over and whisk until smooth.
Sift together flours, baking soda, and salt onto large bowl and set aside.
Place butter in bowl of standing mixer and beat at medium-high speed until creamy, about 1 minute.
Add brown sugar and beat on high until light and fluffy, about 3 minutes.
Stop mixer and scrape down bowl.
Increase speed to medium-high and add eggs one at a time, beating 30 seconds after each addition.
Reduce speed to medium; add sour cream and vanilla and beat until combined, about 10 seconds.
Stop mixer and scrape down bowl.
With mixer on low, add about one third of flour mixture, followed by about one half of chocolate mixture.
Repeat, ending with flour mixture; beat until just combined, about 15 seconds.
Do not overbeat.
Remove bowl from mixer; scrape bottom and sides of bowl and mix gently to be certain all ingredients are combined.
Divide batter evenly among cake pans, smooth batter to edges of pan with angled spatula.
If baking three 8-inch cakes, place two pans on lower-middle rack and one on upper-middle rack.
Bake until skewer inserted in center comes out clean, 20 to 23 minutes for 8-inch cakes.
Cool on wire rack 15 to 20 minutes.
Run knife around pan perimeter to loosen.
Invert cakes onto large plate; peel off parchment, and reinvert onto lightly greased rack.
Cool completely before frosting.
Servings: Serve
Time preparation: 20 min.
Time total: 45 min.