Preheat oven to 375F degrees. In a large bowl, stir together flour, sugar, baking powder and salt until combined.
Add in the chocolate chips. Give it a stir to coat the chips in the flour mixture.
In another mixing bowl, combine the rest of the ingredients (butter, oil, eggs, milk and vanilla.) Whisk together well.
Pour the dry ingredients in with the wet ingredients and stir just until everything is combined and moistened.
Line a muffin pan with cupcake liners (or spray with nonstick cooking spray).
Fill with batter (about 3/4 of the way full).
Now, to make these extra pretty, I like to take some extra chocolate chips and put two or three onto the tops of the muffins. I just think it makes 'em look nicer when they are all done.
Bake at 375F for about 15-18 minutes.
Stick a toothpick in them to check for doneness. They should spring back to the touch when finished.
Video
Notes
These can easily be made into mini muffins as well (you'll just have to adjust the cooking time accordingly).
Also, use your favorite type of chocolate chips. I prefer Milk Chocolate but often I have leftover bags of semi-sweet or mini chocolate chips and I'll use those sometimes.