Ingredients:
For the cake:
•3 cups all-purpose flour
•1/2 teaspoon kosher salt
•1 tablespoon baking powder
•1/2 stick unsalted butter, room temperature
•1 tablespoon vanilla extract
•2 cups granulated sugar
•1/2 cup canola or vegetable oil
•3 large eggs plus 4 yolks, at room temperature
•1 cup lowfat buttermilk
For the filling:
•2 large egg whites, at room temperature•2/3 cup granulated sugar•1/4 teaspoon cream of tartar
•1 teaspoon vanilla extract
Instructions:
For the cake:
•Preheat oven to 325 degrees, and grease a 12-cup Bundt pan with nonstick cooking spray.
•Sift flour, salt, and baking powder into a medium bowl and set aside.
•In a stand mixer fitted with the paddle attachment, cream together butter, vanilla and sugar on medium speed until very light and fluffy, about 3 to 4 minutes.
•Add the canola oil and beat until light and fluffy.
•Next, add eggs and egg yolks one at a time, and beat until fully incorporated, about 1 minute.
•Add the flour mixture and buttermilk to the batter in 3 alternating additions, starting and ending with the buttermilk. Beat just to combine.
•Spoon the batter into the prepared pan using a spatula to smooth the top.
•Bake for 60 minutes, or until toothpick inserted into cake comes out clean.
•Let cool in pan on wire rack for 10 minutes, then invert onto rack, remove the pan and let cool completely.
•Once cooled, turn the cake upside down on a cutting board.
•Using a melon baller, scoop out several mounds of cake through the underside, being sure not to cut through top or sides of cake.
For the filling:
•In a medium glass bowl, using a whisk, combine egg whites, sugar and cream of tartar.
•Place the bowl over a double boiler, and whisk constantly until sugar dissolves and the egg whites are just above room temperature, about 3 minutes.
•Remove bowl from the double boiler, and use an electric hand mixer fitted with a whisk attachment on medium-high speed to whip the mixture until stiff glossy peaks form, about 6 minutes.
•Add vanilla and whisk to combine.
•Using a large piping bag fitted with a large, round tip, fill the hollowed out sections of the cake.
•Flip the cake onto a serving platter and dust with powdered sugar before serving.