PREHEAT oven to 350˚. Butter and lightly flour 3 – 8 inch layer pans. (Easy removal: butter pans, line pan bottoms with parchment paper, butter top of paper and lightly flour, shake out excess flour)
SIFT Swans Down once, measure; set aside.
MELT unsweetened chocolate in small microwave-safe bowl; stirring at 30 second intervals until melted (no longer than 1 minute). Stir until smooth; set aside to cool.
CREAM butter until smooth in large bowl. Add brown sugar and eggs. Beat with mixer till light and fluffy. Beat in vanilla extract and chocolate, then baking soda and salt.
ADD flour alternately with sour cream, beating until smooth. Pour in boiling water next, stirring with spoon till blended. (batter will be very thin)
POUR into 3 – 8 inch layer prepared pans.
BAKE about 20 – 25 minutes or until tester inserted in center comes out clean.
COOL in pans approximately 10 – 15 minutes. Remove cake layers and place on rack to complete cooling.
TIP: Select the 2 layers that are the most level to be the bottom 2 layers. If domed, carefully slice off dome part.
Chocolate Fudge Frosting
PLACE chocolate and heavy whipping cream in small microwavable bowl, microwave on high for 30-second intervals, stirring well after each interval (approximately 1 minute total cooking time). Let cool for 30 minutes.
BEAT butter and chocolate mixture with mixer until smooth in large bowl. Add vanilla extract and milk. Gradually add sugar, beating well until all is blended. If needed, add more milk to achieve correct spreading consistency. Once smooth, do not continue to beat.
FROST cake immediately.