chocolate and ginger bundt cake

I found the basis of this recipe on the BBC Good Food site - I made it as per the instructions the first time, but they included more spices than I liked, and stem ginger and its syrup, so I've amended it a bit. I don't bother with a glaze - it really doesn't need it, in my opinion. It's a really nice cake.

100g unsalted butter , plus extra for the tin
70g golden syrup
50g dark treacle
100g dark muscovado sugar
125g dark chocolate
1/2 tsp grated fresh ginger
65ml Guinness or stout
½ tsp bicarbonate of soda
135g plain flour , plus a little extra for dusting the tin
2/3 tsp baking powder
1 tsp ground cinnamon
2 medium eggs , beaten

(I don't bother with a glaze,but if you did this is what you need)
1 lemon , juiced
100g icing sugar , sifted

Heat the oven to 160C/140C/gas 3. Butter the inside of a 1 litre bundt tin and lightly dust the inside with plain flour, tipping out the excess. I find it best to melt some butter and brush it into every crevice - otherwise, in my experience, you miss a bit.

Put the butter, golden syrup, treacle, brown sugar and chocolate into a pan. Heat to melt the butter and chocolate and dissolve the sugar. Add the stem ginger and Guinness, heat to hot but not boiling and mix well. Take off the heat, whisk in the bicarb (it will foam), and leave to cool slightly.

Sift the flour, baking powder and spice with a pinch of salt into a large bowl. Add the grated ginger. Whisk the eggs and the cooled golden syrup mixture into the dry ingredients in three batches, mixing well until completely smooth. Pour the batter into the prepared tin. Tap on the work surface to release any large air bubbles and bake for about 45-50 minutes or until well risen and a wooden skewer inserted into the middle comes out clean.

Remove from the oven and rest in the tin for no more than 2 minutes, then turn out onto a cooling rack and cool completely. Wrap the cold cake in clingfilm and leave overnight or a couple of days before glazing to allow the spice flavours to develop.

(Optional)
To glaze, transfer the cake to a baking paper- covered baking sheet. Warm the ginger preserve (or apricot jam) in a small pan and use to brush over the surface of the cake. Pour the lemon juice into a small pan and heat gently until just boiling. Add the icing sugar and stir until melted and smooth. Leave the lemon icing to cool for 2-3 minutes then brush all over the surface of the cake in an even layer. Slide the cake back into an oven heated to 160C/fan 140C/gas 3 for 5 minutes until the glaze has become translucent. Leave until the icing has set before serving.