Sticky gingerbread

Ingredients 225g/8oz/2 cups plain (all-purpose) flour 10ml/2 tsp ground ginger 5ml/1 tsp mixed (apple pie) spice Pinch of salt 2 pieces preserved stem ginger, drained and chopped 115g/4oz/1/2 cup vegan butter 115g/4oz ½ cup dark muscovado (molasses) sugar, 275g/10oz/scant 1 cup black treacle (molasses) 2 vegan eggs beaten 2.5ml/1/2 tsp bicarbonate soda 30ml/2 tbsp vegan