• Dry Breadcrumbs, for pan
• 1 cup unsalted butter, room temperature
• 1 1/2 cups sugar
• 2 teaspoons finely grated lemon zest
• 1 tsp vanilla extract
• 1 cup all purpose flour
• 1 cup cornstarch
• 1 tsp baking powder
• 1/2 tsp fine salt
• 1/2 cup half and half cream
• 6 large egg whites
• 1 1/2 cups diced fresh rhubarb, tossed with 2 Tbsp flour
• icing sugar for dusting
1. Preheat oven to 350 °F. Grease and dust a 10-cup bundt pan with dry breadcrumbs, tapping out excess.
2. Beat butter until light and fluffy. Add 1 ¼ cups of sugar to butter, ¼ cup at a time, beating after each addition until fluffy. Beat in lemon zest and vanilla.
3. In a separate bowl, sift the flour, cornstarch, baking powder and salt. Add flour mixture, starting and finishing with flour, alternately with half-&-half, blending on medium-low speed after each addition.
4. In a clean bowl, whip egg whites with remaining ¼ cup sugar until they hold a stiff peak when beaters are lifted. Stir a third of the whites into the cake batter, then fold in remaining whites. Quickly fold in rhubarb and scrape into prepared pan. Bake for 60 to 70 minutes, until a tester inserted in the center of the cake comes out clean. Cool for 20 minutes in the pan, and then turn out onto a rack to cool completely. Dust with icing sugar before serving.
5.Cake slices best with a serrated knife.