Preheat your oven to 350°F/175°C. Grease five 8-inch cake pans with non-stick baking spray and line the bottoms with parchment paper. Set aside. If you don't have 5 cake pans, the batter can sit at room temperature for a few hours. Bake as many layers at a time as you can at a time.
In a medium bowl, whisk together 5 cups cake flour, 3 1/2 cups granulated sugar, 1/4 cup unsweetened cocoa powder, 2 tsp baking soda, and 1 tsp fine salt. Set aside.
In a separate, very large bowl, whisk 2 1/2 cups buttermilk, 1 cup vegetable or canola oil, 1 cup (2 sticks) melted and cooled unsalted butter, 4 large eggs, 1 Tbsp vanilla extract or vanilla bean paste, 2 tsp of instant coffee, dissolved in 1 Tbsp warm water, 2 tsp white vinegar, and 2 tsp red gel food coloring (or 2 Tbsp liquid food coloring). Mix on low speed until combined. The mixture may look broken at this stage, but it will come together once the dry ingredients are added.
Slowly mix the dry ingredients into the wet ingredients at a low speed in two additions. Mix until just combined and no visible streaks of flour remain.
Divide the batter evenly between the prepared pans, about 2 1/2 cups or 540g per pan.
Bake for 23-26 minutes, or until a toothpick inserted in the center of the cake comes out with a few moist crumbs.
Remove the pans from the oven and let them cool for 30 minutes. Run a small offset spatula around the edges of the pans, then carefully flip the cakes out and transfer them to a wire rack to cool completely.
Level the top of the cake layers with a serrated knife once they've fully cooled. It'll make the cake a lot easier to stack. If you're making the cake layers in advance, wrap them tightly in plastic wrap and freeze at this stage.