Refrigerate a metal bowl for 5 minutes to get it cold. Preheat the oven to 425 degrees.
In the refrigerated bowl, add the flour, baking soda, cream of tartar, sugar and salt.
Cut the cold butter into small cubes (or use a cheese grater and grate the cold butter) and add to the flour mixture.
Using a pastry cutter, cut the butter in with the flour mixture until the butter is mostly mixed in. It is okay if there are small pieces of butter. Feel the flour mixture with your fingers and "snap" any large chunks of butter between your fingers to make them smaller.
Make a well in the flour in the center of the bowl. Add the beaten egg and buttermilk to the well.
Using a wooden spoon or spatula, mix the wet ingredients into the dry ingredients. Mix just until blended, being careful not to overmix. Fold in the chocolate chips.
Sprinkle about 1/4 cup of flour on the cupboard. Turn the dough out onto the floured counter. Turn the dough over again over so the floured side is up.
Shape a disk that is about 1 1/4 inches thick. Use a knife to cut the disk into 8 triangles, as if you were cutting a pie.
Place the scones on a greased cookie sheet or a nonstick baking mat.
Bake immediately for 12 minutes. Allow the scones to cool for 3-5 minutes, then remove them to a wire rack to cool completely.
Melt the chocolate in a microwave safe bowl for 30 seconds. Stir and continue to melt in 10 second increments until the chocolate is fully melted.
Use a spoon to drizzle the chocolate over the scones. Immediately top with mini chocolate chips and/or coarse sugar.
Allow the chocolate to set, then store in an airtight container.
Notes
The calories shown are based on the recipe making 8 scones, with 1 serving being 1 drizzled scone. Since different brands of ingredients have different nutritional information, the calories shown are just an estimate. **We are not dietitians and recommend you seek a nutritionist for exact nutritional information.**