Put the oil, black treacle, maple syrup and freshly grated ginger in a bowl and beat together with a fork to mix well.
Set aside. Beat the egg in a small bowl and stir in the lactose free milk. In a large bowl, mix the gluten free flour with the bicarbonate of soda, ground ginger, cinnamon and sugar – rub the mixture between your fingers to break down any lumpy bits of sugar. Heat oven to 160C/140C fan/gas 3.
Blend the dates and their liquid to a thick purée in a small food processor. Pour the egg, the mashed bananas and the treacle mixture into the bowl with the gluten free flour.
Stir together briefly with a wooden spoon just until well mixed – the mixture will be soft like a thick batter. Pour it into the lined tin, gently level the mixture and bake for 40-45 mins.
To test if it’s done, insert a skewer in the centre – if the skewer comes out clean with no uncooked mixture on it, and the cake feels firm but springy to the touch, it should be done.
Leave in the tin for a few mins before removing to a wire rack, peeling off the parchment and leaving to cool completely. If you can wait, wrap it well in parchment, then foil. Leave for a day before cutting, as it will become stickier – it will keep moist for 3-4 days.