Delicious devils food muffin filled with chocolate chips. These are very easy to make and use cooking oil and yogurt instead of butter. These chocolate muffins are very moist and rich. There is no need to use an electric mixer. A whisk or wooden spoon is all you need to mix this recipe. If you like a less sweet muffin, decrease the granulated sugar to 1/2 or 1/3 cup. If they are available in your area, try making the muffins with Ghirardelli 60% Cacao Bittersweet Chocolate Chips. They are really good.