Chocolate Marble Cake (Reduced Fat)

Joy of Cooking, p. 942


Preheat oven to 350 degrees.
Grease and flour a 6-cup fluted tube or Bundt pan.
In a small bowl, whisk together until smooth:
1/3 cup unsweetened cocoa
1/3 cup sugar
1/4 cup water
Sift together:
2 1/4 cups flour
1 teaspoon baking powder
1/2 teaspoon baking soda
1/2 teaspoon salt
In a large bowl, beat until creamy, about 30 seconds:
5 tablespoons butter
Gradually add and beat on high speed until lightened in color and texture, 2 to 3 minutes:
1 cup sugar
Whisk together, then gradually beat in:
2 large eggs
1 teaspoon vanilla
Add the flour mixture in along with:
1 cup non-fat yogurt
beating on low speed or stirring with rubber spatula until smooth.
Stir 1 1/2 cups of the batter into the cocoa mixture. Using a large spoon, scoop three-quarters of the plain batter into the bottom of the pan without smoothing the surface. Spoon all of the chocolate batter over the plain batter, without smoothing the surface. Distribute the remaining plain batter on top, spacing the dollops so that some of the chocolate batter shows through. Use a table knife to marble the two batters gently without blending them completely.

Chocolate Ganache Frosting
I added this ganache to the cake, which makes it not so low fat.
Bring to a boil in a small saucepan:
3/4 cup heavy cream
Remove from heat and add:
8 oz semisweet or bittersweet chocolate, finely chopped
Stir until most of the chocolate is melted. Cover and let stand for 10 minutes. Stir or whisk gently until completely smooth. Stir in:
1 tablespoon liqueur (optional)
Let stand until spreadable.