Cake Flour (2 ½ cups): Using cake flour rather than all-purpose flour is non-negotiable for a genuine "velvet" texture. Its lower protein content prevents excessive gluten development, resulting in a much softer crumb.Granulated Sugar (1 ½ cups): Sweetens the batter and acts as an abrasive during the creaming process, punching tiny air pockets into the fats to guarantee a lofty rise.Natural Unsweetened Cocoa Powder (2 tbsp): It is critical to use natural cocoa, not Dutch-processed. Natural cocoa is slightly acidic, which interacts perfectly with the baking soda and buttermilk to help enhance the reddish hue.Unsalted Butter (½ cup, softened) & Vegetable Oil (½ cup): This recipe utilizes a data-backed dual-fat system. The butter provides rich, irreplaceable flavor, while the oil—which remains liquid at room temperature—guarantees the dessert stays extraordinarily moist for days.Large Eggs (2 whole, room temperature): Act as the primary binding agent, providing the necessary structural integrity to hold the fluffy crumb together.Buttermilk (1 cup, room temperature): The high acidity in real buttermilk breaks down tough protein strands in the flour, yielding an incredibly tender bite.Liquid Red Food Coloring (2 tbsp): Provides the dramatic, iconic crimson color. For a deeper red, use a high-quality gel coloring mixed with a teaspoon of water.Pure Vanilla Extract (1 tbsp): Adds deep, floral aromatic notes that bridge the gap between the cocoa and the sweet frosting.Baking Soda (1 tsp) & Distilled White Vinegar (1 tsp): The ultimate secret to this recipe. When combined, they create carbon dioxide gas bubbles that aggressively lift the heavy batter, ensuring a feather-light texture.Fine Sea Salt (1 tsp): Enhances all the surrounding flavors, ensuring the sweetness does not become cloying.For the Cream Cheese Frosting: 16 oz full-fat block cream cheese (softened), ½ cup unsalted butter (softened), 4 cups sifted powdered sugar, and 2 tsp pure vanilla extract.