Heat the oven to 350°F (175°C). Grease and line an 8x4-inch loaf pan with parchment paper. Whisk together the flour, cocoa powder, baking soda, and salt in a medium bowl until no cocoa streaks remain.

In a large bowl, whisk the sugar and eggs for 1 minute until slightly pale. Add the oil, buttermilk, white vinegar, 1 tsp vanilla extract, and red food coloring and whisk until uniform.

Add the dry ingredients to the wet bowl and fold with a rubber spatula in 15 to 20 strokes, stopping as soon as no dry flour is visible.

Scrape the batter into the prepared pan. Bake on the center rack for 50 to 55 minutes, until a toothpick inserted in the center comes out with just a moist crumb. Cool in the pan for 15 minutes, then lift onto a wire rack and cool fully, about 45 minutes.

Beat the softened cream cheese on medium speed for 1 minute. Add the sifted powdered sugar and ½ tsp vanilla extract and mix on low until combined. Add the heavy cream and beat on medium-high for 30 seconds until thick and glossy.

Spread the icing over the cooled loaf, slice into 8 pieces, and serve.