1. Preheat the oven to 350°F. Grease an 8×8-inch baking pan.

2. In a medium bowl, beat the cream cheese and sugar until smooth and creamy. Beat in the egg and vanilla until well combined.

3. In a separate bowl, whisk together the flour, cocoa powder, baking soda, and salt.

4. In a third bowl, mix the buttermilk and red food coloring.

5. Add the dry ingredients to the wet ingredients in three batches, mixing just until combined after each addition.

6. Pour the batter into the prepared baking pan and bake for 25-30 minutes, until a toothpick inserted in the center comes out clean.

7. Allow the red velvet cake to cool completely, then cut it into thin strips, about 1-inch wide.

8. Spread a layer of the cream cheese mixture onto the sushi nori sheet, leaving a 1-inch border on one side.

9. Arrange the red velvet cake strips in a single layer on top of the cream cheese.

10. Carefully roll up the sushi, starting from the side with the cream cheese filling. Moisten the border with water to seal the roll.

11. Slice the roll into 1-inch pieces and serve.