Preheat the oven to 350˚F. Coat an 8x8 inch pan with cooking spray and line it with parchment paper. Set it aside for later.
Add the flour, cocoa powder, baking soda, and salt to a bowl. Mix everything together with a whisk until evenly combined.
In a separate bowl, add in the melted butter, vegetable oil, and sugar and mix. Add in the egg and vanilla extract, whisking until the mixture is combined. Then add a few drops of red food coloring, just enough to turn to mixture red, and mix.
Pour the dry ingredients into the bowl of wet ingredients and mix until everything is combined. Scrape the mixture into the prepared pan and spread it out into an even layer. Bake it in the oven for about 17 minutes. When a toothpick is inserted into the center, it should not have any batter stuck to it.
Remove the red velvet bar from the oven and allow it to cool in the pan for about 10 minutes before transferring it to a wire rack to cool completely.