8ouncesfull fat block cream cheesesoftened to room temperature
1/2cup(1 stick) unsalted buttersoftened to room temperature
3 and 1/2cupspowdered sugar
gel food coloring in desired colors for optional tinting of frosting
Place oven rack on the middle setting and preheat the oven to 350ºF. Grease and flour (or use homemade cake release) two 8" or 9" round cake pans. Set aside.
In a medium size bowl with a handheld mixer or the bowl of a stand mixer fitted with the whisk attachment, whip the egg whites until soft peaks form (approximately 2 minutes). Set aside or remove from mixer bowl and transfer to a smaller bowl.
Sift the flour, cornstarch, cocoa powder, salt, and baking soda together into a medium size bowl. Set aside.
In a large bowl with a handheld mixer or the bowl of a stand mixer fitted with the paddle attachment, cream the butter and sugar together on medium speed until light and fluffy (approximately 2-3 minutes). Add the vegetable oil and beat again until completely incorporated. Add the egg yolks, vanilla extract, vinegar, and food coloring and beat again on medium speed until everything is combined.
Turn the mixer down to low speed and add the dry ingredients in three additions, alternating with half of the buttermilk. Do not overmix batter. Gently fold the whipped egg whites into the batter with a spatula.
Divide batter evenly between the two prepared cake pans. Bake cakes for about 22-24 minutes or until a toothpick inserted in the center comes out mostly clean. Remove from oven and allow cakes to cool completely on a wire rack before assembling.
CREAM CHEESE FROSTING
In a large bowl with a handheld or the bowl of a stand mixer fitted with a paddle attachment, beat the cream cheese and butter together on high speed until smooth and creamy. With the mixer on low, add the powdered sugar, vanilla, and salt.
Increase mixer speed to medium-high and beat for 2 minutes.
ASSEMBLE THE CAKE
If you'd like colorful layers inside your cake, tint approximately 1/3 cup of frosting the desired color for each layer you'd like colored. For a 2 layer cake, you only need one layer of colored frosting. For a 4 layer cake, you will need 1-3 colors of frosting.
For a 2 layer cake: place one layer, bottom side up, on a plate or cake stand. Using a large zip top bag with the corner snipped off or a pastry bag fitted with a Wilton #12 piping tip, pipe a well with white frosting (or the color of the outside of your cake) around the outside edge of the cake.
Using a spatula or knife, spread an even layer of colored frosting over the entire surface, staying inside the well. Place the second layer on top, bottom side down, and press down on the top lightly. Spread the rest of the white (or desired color) frosting on the cake, beginning with the top and working your way down the sides. Decorate as desired.
For a 4 layer cake: split each layer into two smaller layers using a cake leveler or serrated knife and repeat steps for 2 layer cake, using desired color frostings.
Cake stays fresh covered at room temperature for up to 4 days. Cake may be covered and refrigerated for up to 7 days.
Make ahead: prepare cakes and frosting up to 1 day in advance. Cover cakes tightly and keep at room temperature or in the refrigerator until ready to assemble. Refrigerate prepared frosting in an airtight container until ready to use. Unfrosted cake layers may be frozen, wrapped tightly, up to 2 months. Thaw overnight in the refrigerator before assembling. Frosted cake can be frozen, wrapped tightly, up to 2 months. Thaw overnight in the refrigerator and bring to room temperature before serving.
*I prefer gel color. If you only have liquid food coloring, use approximately 2 Tablespoons.