Make ahead: Make up to three days ahead. Store in an airtight container, or freeze un-iced loaf for up to two months. Thaw at room temperature.
• 175g unsalted butter, chopped, at room temperature
• ¾ cup brown sugar, firmly packed
• 2 free-range eggs
• ½ cup treacle
• 2 cups plain flour
• 1 tsp bicarb
• 1 tblsp ground ginger
• 1 tsp ground cinnamon
• 1 tsp ground nutmeg
• ½ cup milk
• 1¼ cups icing sugar mixture
• 1 tblsp lemon juice
Grease a 14cm x 24cm large loaf pan. Line base and sides with baking paper.
Beat butter and sugar in a small bowl of an electric mixer until light and fluffy. Beat in eggs, one at a time, until combined. Beat in treacle. Transfer to a large bowl.
Stir in half the combined sifted flour, soda and spices until combined. Then stir in half the milk. Repeat with remaining combined flour mixture and milk. Spoon into prepared pan. Smooth over top.
Cook in a moderate oven (180°C) for about 50–55 minutes, or until a skewer inserted into centre comes out clean. Stand for 20 minutes. Turn out onto a wire rack to cool.
To make icing, place icing sugar in a medium bowl. Stir in enough juice to make a thick and smooth consistency. Spoon over cake. Stand until set.