Preheat oven to 400 degrees and line a baking sheet with parchment paper.
In a medium mixing bowl, whisk together all dry ingredients, including sugar.
Using a cheese grater, grate butter into flour mixture. This is much easier and will be the correct consistency if the butter is very cold or frozen. Blend together using your fingers or a pastry cutter.
Lastly, whisk together sour cream and egg in a small bowl. Add to butter and flour mixture and combine until just mixed using your hands. Mixture will be slightly sticky. Do not over mix.
Form into a large ball and then transfers to parchment paper. Flatten using your palm to an 8-9 inch diameter. Cut evenly into 8 slices.
Bake for 15-17 minutes or until tops are on the cusp of browning. Remove, cool and serve warm.
If you've tried this recipe, come back and let us know how it was!