Chocolate Chip Cake

To prepare cake: Preheat oven to 350 degrees F. Coat a 12-cup Bundt pan with cooking spray.

Beat egg whites in a large bowl with an electric mixer on low speed until foamy. Add cream of tartar, increase speed to medium-high and beat until soft peaks form. Gradually add 1/2 cup sugar, beating until stiff but not dry (this can take up to 5 minutes).

Combine the remaining 1 cup sugar, whole-wheat flour, all-purpose flour, baking powder, baking soda and salt in another large bowl. With the mixer on medium speed, beat in buttermilk, oil, vanilla and a heaping spoonful of whites. Fold in the remaining whites and 1/2 cup chocolate chips with a whisk. Scrape the batter into the prepared pan and smooth the top.

Bake the cake until a skewer inserted into it comes out clean, 40 to 50 minutes. Let cool in the pan on a wire rack for 10 minutes. Invert onto the rack and let cool completely.

To prepare chocolate drizzle: Combine 1/3 cup chocolate chips and milk in a small saucepan. Heat over low heat, stirring, until the chocolate is melted and the mixture is smooth. Drizzle over the cooled cake. Serve immediately or let stand until the chocolate is set, about 45 minutes.