Preheat your oven to 180°C (350°F). Grease two 8-inch cake pans and line the bottoms with parchment paper.
Puree the roasted beetroot until smooth and vibrant in color. Measure out 2 cups of the puree and set aside.
In a large mixing bowl, combine the beetroot puree with vegetable oil, sugar, and vanilla extract. Whisk until the mixture is smooth, bright, and slightly glossy, about 2 minutes.
Sift together the cocoa powder, flour, baking soda, and baking powder into a separate bowl. This ensures an even distribution and prevents lumps.
Gradually add the dry mixture to the wet ingredients, alternating with the buttermilk. Begin and end with dry ingredients, mixing gently after each addition until just combined, resulting in a slightly runny, vivid batter.
Pour the vinegar into the batter and fold gently; this reacts with the baking soda, creating a slight fizz and helping the cake rise.
Divide the batter evenly between the prepared pans. Use a spatula to smooth the tops, ensuring even baking and a flat surface.
Bake in the preheated oven for 25 to 30 minutes, or until a toothpick inserted into the center comes out clean and the edges are set. You’ll smell the rich cocoa and beet aroma filling your kitchen.
Remove the cakes from the oven and let them cool in the pans for about 10 minutes. Then, transfer them to a wire rack and cool completely before frosting.
If desired, chill the cakes overnight wrapped loosely in plastic wrap; this helps deepen the flavors and makes slicing easier.
Frost the cooled cakes with cream cheese or mascarpone frosting. Spread smoothly for an elegant, velvety finish that accentuates the deep red color.
Slice a piece, marvel at its blood-red glow, and enjoy this striking, moist, and tender beetroot velvet cake—perfect for a mysterious celebration or a daring dessert adventure.
