Preheat the oven to 350 degrees F. Line 12 muffin cups with paper liners.
Whisk together the flour, cocoa powder, baking powder, baking soda and salt in a large bowl. Stir in the chocolate chips. In a medium bowl, whisk together the milk, brown sugar, butter, oil, vanilla and eggs until smooth.
Quickly fold the milk mixture into the flour mixture with a rubber spatula. Divide the batter evenly among the prepared muffin cups. Bake until a toothpick inserted in the center comes out clean, about 25 minutes. Transfer the muffins from the pan to a wire rack to cool.
When measuring flour, we spoon it into a dry measuring cup and level off the excess. (Scooping directly from the bag compacts the flour, resulting in dry baked goods.)
Copyright 2016 Television Food Network, G.P. All rights reserved.