Preheat your oven to 350°F (175°C).

Grease two 9-inch round cake pans with butter and line them with parchment paper. Grease the paper as well, then dust lightly with cocoa powder for an extra smooth release.

In a medium bowl, sift together the all-purpose flour, cocoa powder, baking powder, baking soda, and salt. Sifting helps keep the batter light and airy while preventing lumps.

In a large mixing bowl or stand mixer, beat the softened butter on medium speed for 3-5 minutes until it turns light and fluffy.

Gradually add the granulated sugar and continue beating for 1-2 minutes until well combined. This step ensures the cake has a soft, tender crumb.

Add the eggs one at a time, mixing for one minute after each to ensure proper incorporation and a stable batter.

Mix in the vanilla extract for added depth of flavor.

In a separate measuring cup, combine buttermilk, white vinegar, and purple gel food coloring. The vinegar reacts with the baking soda, creating a fluffy texture, while the food coloring gives the cake its signature deep purple hue.

Add the dry ingredients in three parts, alternating with the buttermilk mixture in two parts. Start and end with the dry ingredients, stirring only until just combined to maintain a light texture. Avoid overmixing, as it can result in a dense cake.

Scrape down the sides of the bowl to ensure all ingredients are evenly blended.

Pour the batter evenly into the prepared cake pans, ensuring a smooth, level surface.

Lightly tap each pan on the counter to release any trapped air bubbles.

Place the pans in the preheated oven at 350°F (175°C) and bake for 22-25 minutes. Begin checking at 20 minutes by inserting a toothpick into the center if it comes out clean, the cakes are done.

Take the cakes out of the oven and let them rest in the pans for 10 minutes. Then, carefully transfer them to a wire rack to cool completely before applying frosting.

Melt the white chocolate in a double boiler or microwave in 15-second intervals, stirring until smooth. Let it cool slightly.

In a mixing bowl, blend the softened cream cheese and butter until smooth and creamy.

Mix in the vanilla extract and melted white chocolate, blending until smooth and luscious.

Place one cooled cake layer on a serving plate and spread a thin layer of frosting on top.

Add the second cake layer and cover the entire cake with the remaining frosting. Use an offset spatula to create a smooth finish or decorative swirls.

For an extra pop of purple color, tint some frosting with purple gel food coloring and add decorative piping.