Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners or grease it lightly.
In a large mixing bowl, whisk together the flour, cocoa powder, sugar, baking powder, baking soda, and salt until well combined.
In another bowl, mix the vegetable oil, eggs, vanilla extract, and buttermilk until smooth.
Pour the wet ingredients into the dry ingredients and stir until just combined. Do not overmix; a few lumps are okay.
Gently fold in the chocolate chips.
Divide the batter evenly among the muffin cups, filling each about 2/3 full.
Bake for 18-20 minutes, or until a toothpick inserted into the center comes out clean.
Allow the muffins to cool in the pan for 5 minutes before transferring them to a wire rack to cool completely.