Preheat oven to 350ºF and line a large baking sheet with parchment paper; set aside.
In a large bowl whisk together add flour, sugar, baking powder, salt, cinnamon and nutmeg; set aside.
Grate frozen butter (or coconut oil) into large bowl of dry ingredients. Using dough blender, work butter into flour mixture until a grainy, meal texture forms. If using food processor, pulse dry ingredients with butter or coconut oil until pieces are broken down.Remove blade before moving on to the next steps.
Make the streusel: in a small bowl combine butter, brown sugar, flour, oats and cinnamon until combined – mixture should be able to clump together.
Gently stir in the milk, apple cider vinegar and vanilla to bowl of dry ingredients – be careful not to over work the dough. Gently fold in diced apples – dough should come together and be somewhat sticky but not too dry. If it feels on the drier side, add a splash of milk.
Shape dough into large circle, about 8″ in diameter, on prepared baking sheet. Using a large, sharp knife, make 8 triangle slices into dough. Bake for 17-20 minutes, then remove from oven to re-cut slices and pull apart triangles slightly. Bake for another 5 minutes, until edges and tops are lightly browned.
Let scones cool on baking sheet for 5 minutes before transferring to wire rack to cool completely. Scones will stay fresh in airtight container up to 3 days.