Step 1: Preheat your oven to 375°F (190°C). Line a 15x10-inch jelly roll pan with parchment paper, extending the paper over the short ends for easy lifting. Grease the parchment paper and lightly flour it.
Step 2: In a large bowl, whisk together the flour, granulated sugar, cocoa powder, baking soda, and salt. Set aside.
Step 3: In a separate medium bowl, whisk the eggs until light and foamy. Add the buttermilk, vegetable oil, vanilla extract, red gel food coloring, and white vinegar. Whisk until well combined and the color is uniform.
Step 4: Gradually add the wet ingredients to the dry ingredients, mixing on low speed until just combined. Be careful not to overmix the batter.
Step 5: Pour the batter evenly into your prepared jelly roll pan, spreading it to the edges with an offset spatula. Bake for 12-15 minutes, or until the cake springs back when lightly touched in the center.
Step 6: While the cake is baking, lay a clean kitchen towel flat on your counter. Generously sprinkle the towel with powdered sugar.
Step 7: As soon as the cake comes out of the oven, immediately invert it onto the powdered sugar-dusted kitchen towel. Carefully peel off the parchment paper.
Step 8: Starting from one short end, carefully and tightly roll the warm cake (along with the towel) into a spiral. Place the rolled cake, seam-side down, on a wire rack and let it cool completely to room temperature. This step is crucial to prevent cracking.
Step 9: While the cake cools, prepare the cream cheese frosting: In a large bowl, beat the softened cream cheese and unsalted butter together until smooth and creamy. Gradually add the 4 cups of powdered sugar, one cup at a time, beating until smooth after each addition. Mix in the vanilla extract until fluffy. Do not overbeat.
Step 10: Once the cake is completely cool, gently unroll it. Spread the cream cheese frosting evenly over the entire surface of the cake, leaving about a 1-inch border plain on one of the short ends.
Step 11: Starting from the opposite short end, carefully and tightly re-roll the cake, this time without the towel. Ensure it’s a snug roll.
Step 12: Wrap the finished Red Velvet Cake Roll tightly in plastic wrap and refrigerate for at least 1-2 hours, or until the frosting is set and the cake is firm. This makes for cleaner slicing. Before serving, dust with additional powdered sugar, if desired, or garnish with chocolate shavings or fresh berries.