12Tablespoons(170g) unsalted buttersoftened to room temperature1
1cup(240mL) heavy creamroom temperature1,3
6large egg whitesroom temperature1
2 and ½teaspoonsvanilla extract
red food coloring2
blue food coloring2
½cup(113g) unsalted buttersoftened to room temperature
2cups(240g) powdered sugar
2Tablespoons(30mL) milk or cream
Place oven rack on the middle setting and preheat the oven to 350ºF (177ºC). Generously grease and flour (or use homemade cake release) a 10" bundt pan.
In a large bowl with a handheld mixer or the bowl of a stand mixer fitted with the paddle attachment, combine the flour, cornstarch, sugar, baking powder, and salt. Blend ingredients together on low until completely combined, about 1 minute. Add the room temperature butter and beat mixture on low speed until it resembles sand. Scrape down the sides and bottom of the bowl with a spatula and mix again on low for a few seconds until thoroughly combined.
Combine the heavy cream, egg whites, and vanilla extract in a large container with a spout (like a 2-cup glass measuring cup) and mix gently with a fork until blended. With the mixer speed on medium-low, add half of the milk mixture (about 1 cup) to the crumb mixture and mix until blended. Add the remaining milk mixture to the batter and beat again on medium-low until everything is incorporated. Turn the mixer off, scrape down the sides and bottom of the bowl with a spatula, and increase mixer speed to medium. Beat the batter for about 30 seconds until batter is smooth.
Pour about ¼ of the batter into one small bowl, and another ¼ of the batter into another small bowl (these are the portions you will color). You should be left without about half of the batter in your mixing bowl. Set that aside.
Add a bit of red food coloring to one of the small bowls, stir, and add more coloring until it is to your liking. Repeat with the second bowl and the blue coloring. Using a spoon or spatula, add a few dollops of each color batter to the bottom of the bundt pan. Pour about ⅓of the white batter over the dollops. Repeat again until you run out of batter. Tap the bundt pan gently on the counter to allow layers to settle, then bake for 38-40 minutes, or until a toothpick inserted in the center comes out clean.
Remove from oven and allow to cool for 10 minutes on a wire cooling rack. Using oven mitts, carefully flip the bundt cake onto your serving dish/platter. To do this: flip the serving dish/platter over and place on top of the cooling bundt pan. Flip everything over and allow cake to cool completely in the pan, sitting on the serving dish. When cake is completely cool, lift pan off of the cake.
In a large bowl with a handheld mixer, or a stand mixer fitted with the paddle attachment, beat the butter on medium speed until creamy, about 2 minutes.
With the mixer on low, add in the powdered sugar, vanilla, and milk or cream. Increase mixer speed to medium and beat until completely smooth, about 3 minutes. If frosting is too stiff, add more milk. If it is too thin, add more powdered sugar. Add salt to taste.
Decorate cake as desired. Cake stays fresh covered at room temperature for up to 4 days. Cake may be covered and refrigerated for up to 7 days. Cake freezes well, up to 2 months. Wrap in plastic wrap, then in foil, then place in a large freezer bag or freezer-safe container. Thaw in the fridge overnight.
Room temperature ingredients: it is imperative to use room temperature ingredients in this recipe. Allow ingredients to sit out at room temperature at least 45 minutes before beginning.
Food coloring: I prefer gel food coloring. My favorite is AmeriColor.
Cream: I strongly encourage using cream in this recipe. It keeps the crumb moist and dense and adds a creaminess to the overall texture of the cake.