Add the butter and powdered sugar to a bowl of a stand mixer fitted with a paddle attachment. Beat until combined.
Add the cream cheese to the mixer and beat again until light and fluffy, scrape down the sides of the bowl using a rubber spatula and beat again.
Red Velvet Mug Cake
In a medium-sized mixing bowl, add the flour, sugar, cocoa powder, baking soda, baking powder, and salt. Stir to combine using a small whisk.
Into a small bowl or jug, add the oil, buttermilk, vanilla, and vinegar. Whisk to combine.
Pour the wet ingredients into the dry, and mix them using a whisk making sure there are no lumps.
Add two drops of red food coloring to the smooth batter and stir to combine. Adjust the quantity if needed.
Divide the cake batter between the mugs and cook in the microwave on high for 1 minute and 30 seconds. The cakes are cooked when the edges of the cake have pulled away slightly from the mugs and the center is no longer runny.
Spoon the frosting onto the hot mug cakes and decorate with sprinkles, serve immediately.