Preheat the oven to 350ºF. Grease a 9x5 inch loaf pan or line with parchment paper.
In a large bowl, or the bowl of a stand mixer, cream together the butter, sugar and cream cheese until light and fluffy. Add in the eggs one at at time, scraping down the bowl between additions. Add the vanilla and beat to combine.
In a separate bowl, combine the flour, cocoa, baking powder, baking soda and salt. In another bowl or measuring cup, combine the buttermilk and red food coloring.
Beat ⅓ of the flour mixture into the butter mixture, followed by half of the buttermilk mixture.
Continue by adding another ⅓ of the flour, the remaining buttermilk, then the remaining flour, beating just until combined.
Pour the the red velvet batter into the prepared loaf pan.
Bake until a tester comes out clean, 50-60 minutes. Let cool completely before drizzling with cream cheese mixture.
For the cream cheese drizzle, mix together all ingredients and adjust the consistency by adding more sugar or more corn syrup.