Preheat your oven to 350°F (177°C) and line a standard 12-cup muffin tin with paper liners. Since this recipe yields 14 cupcakes total, you’ll need to bake the remaining two in a second, smaller batch.

In a medium mixing bowl, using either a hand mixer or a stand mixer fitted with the whisk attachment, beat the two egg whites on high speed until soft peaks form. This should take about 2–3 minutes. (If you’d like a visual reference, see the soft peaks photo in the yellow cupcakes with milk chocolate frosting post.) Once whipped, set the egg whites aside.

Sift together the flour and cornstarch to ensure they are fully combined. In a separate medium bowl, whisk the sifted mixture with the baking soda, cocoa powder, and salt. Set aside.

In a large bowl using a mixer fitted with the paddle attachment, beat the softened butter on high speed for about 1 minute until smooth and creamy. Add the granulated sugar and continue to beat on high for 2 more minutes until the mixture is fairly well creamed. Use a silicone spatula to scrape down the sides and bottom of the bowl as needed. Add the oil and mix on high for another 2 minutes. The butter may separate slightly or appear uneven when combined with the oil—this is completely normal.

Add in the two egg yolks and vanilla extract, then beat on medium-high speed until fully incorporated. Scrape the bowl again as needed. Mix in the vinegar and red food coloring, adjusting the amount until you reach your preferred shade (about 2 tablespoons is typically enough). With the mixer on low speed, add the dry ingredients in three portions, alternating with the buttermilk. Begin and end with the dry mixture, mixing only until just combined with each addition. Be careful not to overmix.

Gently fold the whipped egg whites into the batter using a rubber spatula or wooden spoon. The finished batter should be smooth, silky, and slightly thick. If you notice some small pieces of butter still visible in the batter (as occasionally happens), don’t worry—they will melt during baking and add extra richness to the cupcakes.

Spoon the batter into the prepared cupcake liners, filling each about halfway to two-thirds full. Bake for 20–21 minutes, or until the tops spring back when lightly pressed and a toothpick inserted into the center comes out clean. Avoid overbaking, as that can dry out the cupcakes. Let them cool in the pan for about 5 minutes before transferring them to a wire rack to cool completely.

While the cupcakes cool, prepare your cream cheese frosting. Once the cupcakes are fully cooled, frost them just before serving. A Wilton #12 round tip works well for piping the frosting—avoid using a star tip, as this particular frosting is a bit too soft to hold detailed shapes.