01 - Preheat oven to 320°F. Line a 2 lb loaf pan with parchment paper.
02 - In a bowl, whisk together flour, baking powder, salt, and ginger if using.
03 - Beat butter and brown sugar until light and fluffy.
04 - Gently heat golden syrup and optional treacle until pourable but not hot.
05 - Beat the warmed syrup into the butter mixture until combined.
06 - Add eggs one at a time, beating thoroughly after each addition.
07 - Fold in dry ingredients alternately with milk, beginning and ending with dry ingredients; mix until just incorporated.
08 - Transfer batter to prepared pan and smooth the surface.
09 - Bake 45 to 55 minutes, or until a skewer inserted in center comes out clean.
10 - Allow to cool in pan for 10 minutes, then transfer to wire rack to cool completely.