Step 1

Preheat the oven to 350°F. Grease two 8-inch round cake pans.

Step 2

Beat the butter and sugar until the mixture is light and fluffy.

Step 3

Add the eggs and vanilla extract. Mix well until combined.

Step 4

Sift the flour with the baking powder and salt.

Step 5

Add these dry ingredients to the butter mixture in two additions, alternating with the buttermilk.

Step 6

Divide the batter evenly between the two pans.

Step 7

Bake the cakes for 25-30 minutes, until a toothpick inserted in the center comes out clean.

Step 8

Allow the cakes to cool for 20 minutes before taking them out of the pan. Let them cool completely on a rack before frosting.

Step 9

Place the chocolate and cream in a heat safe bowl and place it over a pot of barely simmering water. Stir the chocolate and cream occasionally, until all the chocolate has melted and the mixture is smooth.

Step 10

Remove the bowl from the heat and whisk in the sour cream, vanilla and salt. Let the mixture cool completely to room temperature, stirring occasionally (you can chill the mixture for a few minutes to the setting process, then let it continue to cool at room temperature).

Step 11

Once cooled to a thicker consistency, whisk by hand to thicken until spreadable consistency (do not whip vigorously or with electric beaters).