Preheat the oven to 425˚F.
In a medium bowl, combine the flour, salt sugar baking powder and cream of tartar. Pour into a food processor, and add the shortening. Pulse to mix until the mixture resembles coarse meal.
Stir in the cheese with a fork. Mix in the milk until fully combined. Fold in the apples.
Turn the dough onto a floured surface, and flatten into a rectangular shape. Cut the dough into squares.
Place the dough onto a ungreased baking sheet, and bake for around 15 minutes, or until golden brown.