Pre-heat oven to 375 degrees
Prepare a cast iron skillet or a baking sheet. I used butter to grease a cast iron skillet. Or you can use a baking sheet lined with parchment and buttered.
In a large mixing bowl, measure out flour and make a "well" in the middle of the flour. Place the melted butter, beaten egg, salt, sugar, baking soda and orange zest and combine well into the flour.
Add chocolate chips to incorporate.
Add the buttermilk. Stirring with a spoon until you need to get in with your hands and then kneed until all the flour is incorporated. It will start out sticky.
On a clean work surface, spread out a little flour.
Dump out bread mixture and kneed a little more until you can form a round loaf and all the flour is mixed in.
I use a 10 inch cast iron skillet so my loaf was about 8 inches in diameter and about 3 inches thick. If you are using a baking pan, use the same diameters.
Before baking melt a little more butter (about 2 tbs) and brush on top of bread and sprinkle with another tablespoon of sugar. Cut a large "+" sign in the middle of the bread.
Bake in a 375 degree oven for 45 minutes or until a knife comes out clean.