Place the butter and soft light brown sugar in a mixing bowl. Whisk until creamy.
Add the eggs, vanilla and chopped stem ginger. Whisk again to combine.
Sift in the self-raising flour, baking powder and ground ginger and fold through.
Transfer the batter to a piping bag and snip off the end to create a 2cm-wide hole. Pipe the batter into the greased doughnut moulds. You have enough for 12 in this donut pan, so I piped and baked six, then piped and cooked the second set.
Bake for approximately 10 minutes until risen and firm. Transfer to a wire rack to cool completely.
To make the glaze
Sift the icing sugar into a mixing bowl and add the lemon juice.
Mix to a thick, pourable icing.
Take the completely cooled doughnuts and dip half way into the glaze, then back on the wire rack to set.
Scatter with the crushed gingernut pieces and leave to set