Just like Mac&Cheese, every cook has thier own recipe, sour cream would add more butter fat and moisture:
2 cups flour
2 teaspoons baking powder
1/2 teaspoon baking soda
1/4 teaspoon salt
1/2 cup cold butter
1 egg, separated
3 tablespoons honey
1/3 cup buttermilk
1 teaspoon water
2 tablespoons granulated sugar
1/4 teaspoon ground cinnamon
Preheat oven to 400 degrees F.
In a large bowl, stir together flour, baking powder, baking soda, and salt. Cut in butter until mixture resembles coarse crumbs.
In small bowl, beat egg yolk with honey and buttermilk until blended, add to flour mixture, blending lightly just until mixture clings together.
With floured hands, lightly shape dough into flattened ball. Roll out on floured surface into a circle 1/2 inch thick. Using floured knife, cut into 8 to 12 wedges. Place on greased or non-stick baking sheet.
In a small bowl, lightly beat egg white with water.
In another bowl, blend sugar and cinnamon. Brush scones lightly with egg white, then sprinkle with cinnamon sugar.
Bake until golden brown (10 to 12 minutes). Serve warm.