Sift the flour, salt, sugar, baking powder, and cream of tartar together into a large bowl.
Grate the cold butter into the dry mixture. Toss the butter and flour as you go along to prevent clumping.
Crumble the butter and flour together until you create a finer sandy texture. You can just pulse in a food processor if desired.
Mix the egg, cream, and milk together and reserve two tablespoons in a small bowl (this will be used for the egg wash).
Create a well in the middle and pour in the milk mixture and mix until combined. This will be a sticky mixture so I always try to keep one hand in the bowl and one hand free and clean.
Place the dough on a floured surface and roll out to about 3/4 an inch or more thick. (no one wants a flat scone!). Use whatever shaped cutter you'd like and transfer the scones to a parchment-lined baking sheet.
Brush tops with the reserved egg wash and place in oven to bake for about 20 minutes or until golden.