Place the flour and baking powder into a large bowl, rub in the butter until it resembles fine breadcrumbs and stir in the finely chopped celery, 100g of the grated cheese and the chopped walnuts.
Break the egg into a measuring jug, lightly beat and make up to 150ml with the milk.
Add all but a small amount (which you should reserve to glaze the tops of the scones).
Mix gently until you have a soft dough.
Knead lightly on a floured surface and roll out to approx. 2cm thick, cut into 6cm rounds and place on the baking tray.
Brush the tops with the reserved egg mix and sprinkle with the remaining cheese, bake for 12-15 mins until well risen and golden.
Cool on a wire rack.
Mix together the softened butter and parsley and serve the scones warm, split in half and topped with the butter and the celery sticks on the side.
Recipe by appetite magazine at https://www.appetitemag.co.uk/cheese-celery-and-walnut-scones-with-parsley-butter/