Pre-heat oven to 400° (200° celsius), grease and flour a 6 or 12 muffin tin.
In a large bowl whisk together flour, sugar, chocolate chips, cocoa powder, baking soda, baking powder and salt until combined.
In a medium bowl whisk together egg, yogurt, milk, vanilla, coffee and oil until combined.
Pour wet mixture into dry mixture and stir just until combined (stir approximately 15-16 times). Batter will be lumpy.
Fill muffin tins almost to the top. Sprinkle with a few extra chips if desired.
Bake at 400° (200° celsius) for 5 minutes, then lower heat to 350° (175° celsius) and continue to bake for approximately 15 minutes (a little less for smaller muffins) or until toothpick comes out clean or with a few crumbs attached. Let cool completely. Enjoy!
Notes
If you wish you can substitute buttermilk, sour cream or regular yogurt for greek yogurt. But if you substitute with buttermilk or regular yogurt, because these are not as thick as greek yogurt or sour cream only use 1/4 cup of the milk.The completely cooled Muffins should be stored in an airtight container. In order to keep the muffins from becoming soggy, either line the container with a paper towel and cover the muffins with another paper towel or add a slice of bread to the container to absorb any excess moisture. They will keep for 2-4 days at room temperature.To freeze them, place them in a single layer in a freezer safe air tight container or freeze the muffins on a cookie sheet and then move them to freezer bags. Muffins will keep for up to 2-3 months in the freezer.