Cream the butter, add sugar gradually, and milk very slowly. Mix and sift flour and ginger, and combine mixtures. Spread very thinly with a broad, long-bladed knife on a buttered, inverted dripping pan. Bake in a moderate oven. Cut in squares before removing from pan. Watch carefully and turn pan frequently during baking, that all may be evenly cooked. If mixture around edge of pan is cooked before that in the centre, pan should be removed from oven, cooked part cut off, and remainder returned to oven to finish cooking.