Pre-heat your over to 160°C/140°C fan. Line a muffin tin with 16 cupcake cases.
Put the butter (110g), golden syrup (110g) and black treacle (110g) into a sauce pan and heat gently until the butter has melted. Mix to combine the ingredients.
Add the buttermilk (150ml) to the pan and set aside to cool.
Finely chop the stem ginger (4 balls). Add 1 tsp plain flour and mix to coat the ginger in the flour (this will help stop the ginger from sinking to the bottom of the cake while baking).
Put the plain flour (220g), bicarbonate of soda (1tsp), soft light brown sugar (40g) and ground ginger (4tsp) into a large bowl and mix to combine. Add the buttermilk mixture and egg (1 large) and mix until combined. Finally fold in the chopped stem ginger.
Evenly divide the mixture between the 16 cupcake cases.
Bake for c. 20 minutes, until a skewer inserted in the centre comes out clean.
As soon as you've removed them from the oven while they're still hot, stab each cupcake a few times with a skewer and then brush the tops of the cupcakes with some of the syrup from the stem ginger.
Put the cupcakes onto a cooling rack to cool completely.
Once the cupcakes have cooled brush them a second time with the stem ginger syrup to get the tops really sticky.