Preheat your oven to 350°F (175°C) and grease a donut pan with cooking spray.
In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt until well combined.
In another bowl, mix the buttermilk, vegetable oil, egg, and vanilla extract until smooth.
Pour the wet ingredients into the dry ingredients and stir until just combined. Be careful not to overmix.
Gently fold in the chocolate chips.
Spoon the batter into the prepared donut pan, filling each cavity about 2/3 full.
Bake for 10-12 minutes or until a toothpick inserted into the center comes out clean.
Allow the donut rolls to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.