2 c. flour
1 1/2 tsp. baking powder
1/2 tsp. baking soda
8 tbsp. butter
3/4 c. sugar
1 c. plain yogurt or buttermilk
2 lg. eggs
1/2 tsp. vanilla
1 tsp. freshly grated orange peel

CRUMB MIXTURE:

1/2 c. sugar
1/4 c. cocoa
3 tbsp. butter, chilled
2 tsp. orange peel

In a separate bowl, mix crumb mixture by fork or finger tips until crumbly. In a large bowl, mix dry ingredients of cake. In a microwave safe bowl, melt 8 tablespoons butter. Cool to room temperature; add remaining wet cake ingredients. Pour wet mixture into dry ingredients. Stir until just blended. Spread 1/2 of cake batter into a greased 9 x 5 x 3 inch loaf pan.

Sprinkle with 1/2 crumbs. Top with rest of cake batter and then crumbs. Marbelize by upright knife 6-8 times down pan, crosswise. Bake at 350 degrees for about 1 hour. Test with toothpick. Cool in pan at least 30 minutes. Turn out of pan and turn over. Cool completely. Wrap airtight.