Preheat oven to 350. Spray 3 - 8 inch cake pans with baking non stick spray
Combine the semisweet chocolate and 3 tablespoons of the butter in a microwave safe bowl and heat just until melted and smooth. Set aside
In a bowl, whisk flour baking powder and salt, set aside
In a large bowl beat sugar with remaining 11/2 chose butter until light and fluffy about 4 minutes
Add eggs, one at a time beating each one in then add vanilla
Add flour mixture alternating with sour cream and stir until just combined
Remove 2 cups of batter to a medium bowl, add chocolate mixture and stir to combine
Drop batter into prepared pans in even mounds , alternating chocolate and vanilla as shown below
With a butter knife, pull it slowly through each color for a swirl as shown below. To even cake tap pan sharply on counter once or twice.
Bake 20 to 23 minutes until a Toothpick comes out just clean. Cool 15 minutes in pans then turn out onto rack to cool completely
TO FROST, place one layer, upside down on serving plate
Add 3/4 of Whipped White Chocolate Ganache Frosting on cake layer. Recipe attached below
https://cookpad.com/us/recipes/359637-white-chocolate-ganache-whipped-frosting-filling
Place second cake layer, upside down frost with some of the Whipped Chocolate Ganache Frosting. Recipe attached below
https://cookpad.com/us/recipes/352391-whipped-chocolate-ganache-frosting-filling
Place third, top layer upside down on last one. Frost entire cake with the Whipped Chocolate Ganache
Pipe remaining White Chocolate Ganache on top and bottom of cake. Decorate cake with sparkle sugar sprinkles
