Preheat your oven to 325°F (160°C) and line your baking tin with parchment paper.
In a bowl, mix oats, flour, baking powder, spices, and salt.
Gently melt treacle, golden syrup, sugar, butter, and lard (if using) in a saucepan — don’t boil.
Stir the wet mixture into the dry ingredients until combined.
Add the beaten egg and milk, mixing until smooth.
Fold in candied ginger if using.
Pour the batter into the lined tin and smooth the top.
Bake for about 1 hour or until a toothpick comes out clean. Cool completely before slicing.