Preheat the oven to 350°F (175°C). Grease and flour a 9×13 inch sheet pan.
In a large bowl, sift together the flour, sugar, baking soda, salt, and cocoa powder.
In a separate bowl, whisk together the vegetable oil, buttermilk, eggs, red food coloring, vanilla extract, and vinegar until well combined.
Slowly add the wet ingredients to the dry ingredients and mix until smooth.
Carefully stir in the boiling water until the batter is thin and well combined.
Pour the batter evenly into the prepared sheet pan.
Bake for 30 minutes or until a toothpick inserted into the center comes out clean.
Remove the cake from the oven and allow it to cool completely in the pan on a wire rack.
While the cake cools, prepare the cream cheese frosting: In a medium bowl, beat the cream cheese and butter together until smooth and creamy.
Gradually add the powdered sugar, one cup at a time, beating well after each addition.
Add the vanilla extract and beat until the frosting is light and fluffy.
Once the cake has cooled completely, spread the cream cheese frosting evenly over the top.
Slice into 24 squares and serve.