Instructions

1. 1
   Preheat oven to 350 degrees. Lightly spray a 15x10x1" jelly roll sheet pan with non-stick baking spray. Set aside.
2. 2
   In a mixing bowl, sift together the dry ingredients: flour, cocoa powder, and salt. Set aside.
3. 3
   With a hand or stand mixer, combine the oil, granulated sugar, and eggs. Add in the food coloring and vanilla. Mix until smooth.
4. 4
   In a small bowl, stir together the buttermilk and baking soda. Stir together until the baking soda dissolves into the milk. Liquid will become frothy.
5. 5
   With the mixer running, gradually add the dry ingredients, alternating with the buttermilk mixture to the batter in the main mixing bowl. Stop the mixer occasionally to scrape down the sides of the bowl.
6. 6
   Pour the batter into the sheet pan, and smooth out evenly with a spatula. Bake the cake at 350 for 30-32 minutes or until a toothpick inserted comes out clean and crumb-free. Remove cake from oven and let cool to room temperature.
7. 7
   For the frosting: With a hand or stand mixer, cream together the butter and cream cheese until smooth. Add the vanilla and incorporate well. Gradually begin adding the powdered sugar one cup at a time, stopping the mixer to scrape down the sides of the bowl.
8. 8
   Spread the frosting evenly over the top of the cooled sheet cake. Top with any sprinkles of your choice, if desired.