2 Cups cake flour
1 tsp Baking powder
1/2 tsp Baking soda
1/2 tsp Salt
1 tsp Instant espresso or Coffee powder
1/3 cup Unsweetened Dutch process cocoa
1 1/3 cups Sugar
6 tbsp Unsalted butter, at room temperature
1 whole egg
1 egg white
1 cup Nonfat plain yogurt
2 teaspoons vanilla extract
Use a whisk to combine four, baking powder, baking soda, and salt. Sift together. Set aside.
In a large bowl, cream together the butter and remaining 1 cup of sugar until light, about 3 minutes. Gradually add eggs about 1 Tbsp at a time beating constantly for about 2 minutes. Beat in 2 tsp vanilla extract.
Add third of the flour mixture to the butter mixture. Then beat in half of the yogurt at low speed. Keep alternating flour and yogurt and mixing at low speed until just combined.
Measure out 1 1/2 cups of the yogurt batter and stir into the cocoa mixture.
Use a large spoon to fill the bottom of the pan with about three quarters of the white batter placed in dollops. Cover the white batter with dollops of chocolate batter. Top the chocolate batter with small dollops of white batter spaced so that the chocolate batter shows through. Use a bread knife to marble the batters together with a circular or zigzag motion; be careful not to blend them too much. Bake for 40 -50 minutes or until the cake starts to pull away from the sides of the pan and a toothpick inserted in comes out clean. With 9 by 5 loaf pan it took me 45 minutes.
Cool for 10-15 minutes on a rack. Unmold the cake. Cool completely before serving or storing.