Preheat the oven to 350 degrees F. Line a baking sheet with parchment paper; set aside.
In a small bowl, whisk together sour cream and egg; refrigerate until needed.
In a separate small bowl, make the cinnamon/sugar topping be stirring together the sugar and cinnamon; set aside.
In the bowl of a food processor fitted with the metal blade, pulse together the flour, sugar, baking soda, baking powder, cream of tartar, salt, cinnamon, and nutmeg until combined about five 1-second pulses. Add butter and toss with a fork to cover in flour mixture. Pulse until mixture looks like coarse cornmeal flecked with pea-sized bits of butter, about 10 to 12 pulses. Transfer mixture to a large mixing bowl.
Add sour cream mixture to flour mixture; fold with spatula until just combined. With rubber spatula, transfer dough to lightly floured work surface. Knead dough 6 to 8 times, until it just holds together. Shape into an 8-inch circle. Sprinkle with cinnamon topping. With a sharp knife or pizza cutter, cut the dough into 8 wedges.
Place wedges on prepared baking sheet and bake 15 to 18 minutes until golden brown. Transfer to a wire rack to cool.
While the scones are cooling, make the spiced glaze. Combine all ingredients in a small bowl and mix until you achieve a thick icing. Drizzle over scones and serve.