4 large egg whites
1/4 teaspoon cream of tartar
1 1/2 cups sugar, divided
5 oz (1 1/4 cups) whole-wheat pastry flour
6.25 oz (1 1/4 cups) all-purpose flour
2 teaspoons baking powder
1 1/2 teaspoons baking soda
3/4teaspoon kosher salt
1/8 tsp cinnamon
1 1/2 cups nonfat yogurt or buttermilk (see Tip)
1/4 cup canola oil
1 tsp vanilla extract
2 tsp Frangelico
1/2 cup mini chocolate chips or chopped chocolate
1/3 cup mini chocolate chips
2 tablespoons low-fat milk
Preheat oven to 350. Spray a Bundt pan with nonstick spray.
Mix flours, baking powder, baking soda, salt, cinnamon, and 1 cup of the sugar together in a large bowl.
Mix yogurt, vanilla and Frangelico and oil together in a small bowl.
Beat egg whites in a medium bowl, gradually adding sugar and cream of tartar, until soft peaks form.
Add yogurt mixture to dry mixture, stirring together only a few strokes. Add a generous spoonful of the whipped whites, and stir a few more strokes. Add remaining egg whites and chocolate chips, and fold very gently until mixture is mostly combined--it's okay if there are a few streaks left, take care not to overmix here.
Pour into Bundt pan, spread batter evenly, and place in oven. Bake 40-50 minutes, until skewer inserted comes out clean. Place pan on a rack and let cool in pan 10 minutes, then invert onto rack and allow to cool completely.
For Drizzle: Melt chips and milk in a microwave at 30-second intervals until smooth and melted. Drizzle over cake. Chocolate will set in about 30-45 minutes.