Preheat oven to 350°F (175°C). Grease two 9-inch round metal cake pans, line the bottoms with parchment paper, then lightly grease and flour the parchment and sides (or use baking spray with flour).

In a medium bowl, whisk together the flour, cocoa powder, baking soda, and salt until evenly combined. Set aside.

In a large mixing bowl or stand mixer fitted with the paddle attachment, beat the softened butter and granulated sugar on medium speed for 3–4 minutes, until light and fluffy. Add the oil and beat another 1–2 minutes until creamy and slightly lighter in color.

Beat in the eggs one at a time on low–medium speed, mixing just until incorporated after each addition. Mix in the vanilla extract, scraping down the sides and bottom of the bowl as needed.

In a small bowl or measuring cup, stir together the buttermilk, white vinegar, and red food coloring. Start with 1 tablespoon of color and add more as needed for your desired shade of red.

With the mixer on low speed, alternate adding the dry ingredients and the buttermilk mixture: add about 1/3 of the dry ingredients, then 1/2 of the buttermilk mixture; repeat, ending with the remaining dry ingredients. Mix just until the batter is smooth and no streaks of flour remain; do not overmix.

Divide the batter evenly between the prepared pans (weigh the pans if you want perfectly even layers). Gently tap each pan on the counter a few times to release large air bubbles. Bake for 25–30 minutes, or until the centers spring back lightly when touched and a toothpick inserted in the center comes out with just a few moist crumbs. Begin checking around 23 minutes.

Place the pans on a wire rack and let the cakes cool in the pans for 10–15 minutes. Run a knife gently around the edges, then turn the cakes out onto the rack and peel off the parchment. Let the layers cool completely, about 45–60 minutes, before frosting.

In a large bowl, beat the softened cream cheese and softened butter together on medium speed until smooth and creamy, 2–3 minutes. Add the vanilla and salt and mix to combine. Gradually add the powdered sugar, 1 cup at a time, starting on low speed to avoid splatters, then increasing speed once mostly incorporated. Beat until smooth and fluffy, 2–3 more minutes. If the frosting is too soft, add a bit more powdered sugar and chill for 15–20 minutes.

If the cake layers are domed, use a long serrated knife or cake leveler to trim them flat, reserving the scraps for garnish. Place one layer on a serving plate or cake stand and spread a generous layer of cream cheese frosting over the top. Set the second layer on top, bottom side up for a flatter top. Apply a thin crumb coat of frosting over the top and sides of the cake and chill for 15–20 minutes to set.

Apply a thicker, even final layer of cream cheese frosting over the top and sides of the cake, swirling the top if desired. Crumble some of the reserved cake scraps and sprinkle around the top edge or over the sides for a classic red velvet look. Chill briefly if you’d like cleaner slices before serving.