1. to make the cake, preheat the oven to 350 degrees. spray two 8-inch round cake pans with nonstick spray, line with wax paper rounds and spray with nonstick spray.

2. whisk the flour, baking powder, baking soda, and salt together in a medium bowl. with an electric mixer on high speed, beat the eggs and egg whites in a large bowl until thickened, about 2 minutes. gradually add the granulated sugar, beating until light and fluff, about 3 minutes. on low speed, add the buttermilk and oil, beating just until blended. add the flour mixture, beating just until incorporated. stir in the chocolate chips.

3. spoon the batter into the pans. bake until a toothpick inserted intothe centers comes out clean, about 35 minutes. let cool in the pans on racks 10 minutes. Invert the layers onto the racks. Peel off the wax the wax paper and let cool completely on the racks.

4. to make the frosting, with an electric mixer at high speed, beat the ricotta, cream cheese, confectioners sugar, orange zest and vanilla in a medium bowl until smooth, about 1 minute.

5. Place 1 cake layer, rounded side down on a serving plate. with a narrow metal spatula, spread 1/2 cup of the frosting over the layer. top withthe remaining layer, round side up. Spread the remaining frosting over the top and side of the cake. sprinkle the pistachios on top of the cake.