Preheat oven to 200 degrees. Keep a cake pan ready.
Combine the flour, sugar, baking powder, baking soda and salt in a bowl and whisk.
Grate the cold butter onto the dry ingredients. Work the butter into the flour till it looks like a coarse meal.
Stir in the chocolate chips.
In a bowl, whisk egg and yogurt till smooth.
Pour into the dry mix and starting pulling out the dough together till it is completely moist and you have a sticky dough.
On a floured surface, pat into a round shape around 3/4 inch thick.
Cut into 6 wedges using a sharp knife. Arrange on the pan leaving 1/2 inch space between each wedge.
Bake for 12-15 minutes till the top becomes golden brown. Cool in the pan for 5 minutes. Serve warm with a cup of tea!
Notes
I substituted yogurt for sour cream. If you have sour cream, then use it. I have halved the recipe, and accordingly adjusted on the yogurt so that I could accommodate the egg in. My dough had a good consistency.