Preheat oven to 400 degrees Fahrenheit. Combine flour, baking powder, salt and sugar in a large bowl. With two knives or a pastry cutter, cut in cubes of butter until mixture is crumbly and the butter is about the size of small peas. Gently fold in the cheese and apples. Add 3/4 cup buttermilk and mix, using a light hand, just until all ingredients are incorporated. Add more buttermilk if the dough does not hold together. Lightly flour a work surface. Remove dough from bowl and pat into a ball. Flatten the dough into a circle 1/2-inch thick. Cut into 8 triangles. Whisk egg and milk in a small bowl. Brush the scones with egg wash. Place scones on an ungreased baking sheet and bake for 18 minutes. Serve warm with butter and/or apple butter. More wickedly delicious and easy apple recipes!