Preheat oven to 425ยบ F (adjust down for convection)
Combine dry ingredients in a large bowl, then cut butter in with a pastry cutter until you've got a bowl of coarse mealy crumbs.
Combine egg, yogurt, and 2T of the milk in a separate bowl, then stir the wet ingredients into the dry until it just starts to come together
Add apple, cheese, and fresh sage
Turn the whole gooey mess out onto a clean, lightly floured counter, then knead gently until it just barely forms a ball. Note: Don't overknead here, or the scones will be tough and chewy, and you dont' want anyone breaking a tooth, do you?
Divide dough in half, then gently form each ball into a six-inch circle and cut each into eight wedges.
Bake on parchment lined baking sheets for 12-14 minutes until golden.