1. Preheat oven to 350°F (175°C). Grease, line with parchment, and flour two 9-inch round cake pans.2. Make the cake: Whisk dry ingredients (flour, sugar, baking soda, salt, cocoa) in a large bowl. Whisk wet ingredients (oil, eggs, buttermilk, coloring, vanilla, vinegar) in a medium bowl.3. Pour wet into dry and mix on low speed until just combined. Do not overmix.4. Divide batter between pans. Bake for 30-35 minutes, or until a toothpick comes out clean. Cool layers completely.5. Make the frosting: Melt the chopped white chocolate in a double boiler or in the microwave at 50% power in 20-second bursts. Stir until smooth. Let cool for 10-15 minutes until lukewarm but still liquid.6. In a large bowl, beat the softened cream cheese and butter on medium-high speed until fluffy (3 minutes).7. Add the cooled, melted white chocolate and beat on low speed until combined.8. Gradually add the powdered sugar and vanilla extract. Beat on medium-high for 2 minutes until smooth and thick.9. Assemble: Place one cooled cake layer on a serving plate. Top with frosting. Add the second layer and frost the top and sides of the cake.