Preheat oven to 375F (190C) and line a baking sheet with parchment paper. Set aside.
Combine flour, sugar, cream of tartar, baking soda, ground cinnamon, and salt in the basin of a food processor (see note 1 if you do not have a food processor).
Scatter butter pieces over the top of the dry ingredients and pulse until butter is cut into the mixture (pebbly pieces of butter will likely still remain, and the mixture should resemble coarse crumbs).
Combine heavy cream and vanilla extract in measuring cup and pour evenly over the dough. Pulse again until dough is just beginning to cling together (don’t overdo it!).
Transfer dough to a clean, lightly floured surface and if it is crumbly work until dough is clinging together.
Fold dough in half over itself and gently flatten. Rotate the dough 90 degrees and fold it over itself and flatten again. Repeat this step 4-5 times, taking care to not overwork the dough.
Form the dough into a 6” disk (approximately 1” tall).
Use a sharp knife and press straight down to cut the dough into 8 even wedges.
Transfer to prepared baking sheet, spacing scones about 2” apart.
In a small dish, whisk together sugar and cinnamon. Set aside.
Use a pastry brush to brush the surface of each scone lightly with heavy cream. Sprinkle lightly with prepared cinnamon/sugar mixture (you do not have to use all of the topping).
Transfer to 375F (190C) preheated oven and bake for 14-15 minutes or until the edges of the scones are just beginning to turn a light golden brown.
Remove from oven and allow to cool on baking sheet before enjoying.