Preheat oven to 350 degrees. Line 24 muffin cups with paper liners and set aside. In a microwave-safe bowl, combine chocolate and butter. Heat for 1 minute and stir. Heat for an additional 30 seconds and stir; repeat heating for 30 seconds and stirring until chocolate mixture is nearly smooth. In a large mixing bowl, beat together the eggs, sugar, water, sour cream, and vanilla. Combine flour and baking soda in a small bowl and add to egg mixture. Add chocolate mixture and beat on high for 2-3 minutes. Fill paper liners 2/3 full of batter. Bake at 350 degrees for 18-20 minutes or until toothpick tests clean. Allow cooling in pans for 10 minutes; remove cupcakes to wire racks and cool completely. To make frosting, combine chocolate and butter in a microwave-safe bowl. Heat for 1 minute and stir. Heat for an additional 30 seconds and stir; repeat heating for 30 seconds and stirring until chocolate mixture is nearly smooth. Cool for 10 minutes. Using a hand mixer beat powdered sugar, sour cream, and vanilla into chocolate mixture on low until smooth. Frost the cooled cupcakes. Store cupcakes in the refrigerator. Garnish with chocolate curls before serving, if desired.

Ready in 50 min