Preheat your oven to 350°F (175°C) and line a muffin tin with paper liners.
In a large bowl, whisk together the flour, cocoa powder, sugar, baking powder, baking soda, and salt.
In another bowl, combine the milk, vegetable oil, and vanilla extract.
Pour the wet ingredients into the dry ingredients and stir until just combined.
Fold in the chocolate chips gently.
Divide the batter evenly among the muffin cups, filling each about 2/3 full.
Bake for 18-20 minutes, or until a toothpick comes out clean.
Let the muffins cool in the tin for 5 minutes before transferring to a wire rack.
Enjoy warm or store in an airtight container.
Optionally, dust with powdered sugar before serving.