Mix the dry ingredients in bowl. Warm the butter in a pan with treacle (don’t let it bubble too much). Add this to the dry ingredients and mix well. Turn into a prepared tin, smooth the surface if necessary. Bake for approximately 35/40 minutes, but watch it carefully. It needs to be cooked but not burned; which is very easy to do. Let it cool for a moment or two to harden off. When it’s firm to touch, turn out onto wire rack. Cut it before it gets really cold – it’s easier; but be careful that you don’t break it into pieces by using a blunt knife!