Simple Chocolate Cake

1 stick unsalted butter
2 1/4 cups light brown sugar
3 eggs
1 1/2 teaspoons vanilla extract
3 ounces unsweetened chocolated, melted
2 teaspoons baking soda
1/2 teaspoon salt
2 1/4 cups sifted Cake flour
1 cup sour cream
1 cup boiling water

Preheat oven to 350 degrees.  Grease and flour 2 9 inch layer pans.  In a large mixing bowl, cream butter till smooth.  Add brown sugar and eggs.  Beat with mixer till light and fluffy.  Beat in vanilla and chocolate, then baking soda and salt.  Add flour alternately with sour cream, beating until smooth.  Pour in boiling water, stirring with spoon until blended.  Pour batter into layer pans and bake approximately 30 minutes or until done.  Cool completely.