Take a microwave-safe mug (around 10-12oz) and add in the milk, vinegar, oil, and vanilla. Give it a good mix with a whisk or fork.
Add the red food color and mix until you have a bold red color (it'll dilute a bit when we add cocoa powder).
Sift in the flour, cocoa powder, baking powder, and salt. Add the sugar. Whisk until a smooth batter forms (no need to overmix).
Microwave on the default setting for 60-90 seconds. Keep an eye on it around the 60-second mark; if there's still wet batter, zap it for another 10-20 seconds.
Let the cake cool for 15 minutes (speed up the process by placing it in the fridge after 5 minutes).
While it cools, use a fork to whip up the cream cheese frosting until it's creamy.
Spread a generous amount of the cream cheese frosting onto the cake.
Serve, and let the indulgence begin!