Preheat the oven to 350F/176C. Spray or butter a 10" bundt pan and set aside.
In a large bowl, whisk together the flour, baking soda, cocoa powder, and salt. Set aside.
Using a handheld or stand mixer fitted with the paddle attachment, beat the butter on high speed until smooth and creamy. Add the sugar and beat on high speed until well combined. Add the eggs, and beat until combined. Beat in the vinegar and the food coloring.
With the mixer on low speed, add the dry ingredients in three additions alternating with the buttermilk, beginning and ending with the dry ingredients.
Pour the batter into the prepared bundt pan and bake for 50 - 55 minutes or until a toothpick inserted into the centre comes out clean with moist crumbs. Let the cake cool completely in the pan on a wire rack before removing and frosting.
For the Cream Cheese Frosting:
Using a handheld or stand mixer fitted with the paddle attachment, beat the cream cheese and vanilla until smooth. Add the sugar and milk. Mix on low speed for a minute and then increase to medium-high speed to beat until well combined. If the frosting is too thick, add more milk to loosen to drizzle consistency.
Drizzle the frosting over the cake. Decorate with sprinkles if desired.