Preheat the oven to 175°C (350°F). Grease and flour a small round cake pan.
In a bowl, sift together flour, sugar, cocoa powder, baking powder, baking soda, and salt.
In a separate bowl, whisk together vegetable oil, buttermilk, egg, vanilla extract, and red food coloring. Gradually add the wet ingredients to the dry ingredients, mixing until smooth.
Pour the batter into the prepared pan and bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean. Let the cake cool completely.
Beat cream cheese, powdered sugar, and vanilla extract until smooth and fluffy.
Spread the frosting evenly over the cooled cake. Chill for 30 minutes before slicing and serving.