Dutch Jewish ginger buns (gember bolus)

I came across these ginger buns (gember bolus) in the cafe of the Jewish Museum in Amsterdam. I googled "ginger bolus", but all I came up with were reports of people choking to death in Thailand. Eventually, I found something which appeared to be related on a blog called Bake My Day! So I contacted the author of the blog where I had found that recipe and she very kindly got back to me with a version of what I was looking for. Needless to say, I then fooled around with the recipe a bit (well, quite a lot) and this is what I came up with.

Ingredients
dough
500g plain flour
7g active yeast
320g milk
30g water
20g brown sugar
20g margarine or butter

syrup
200g brown sugar
200g water

filling
250g ginger crush in syrup

for sprinkling
more brown sugar

Method

1. Put the syrup ingredients in a small saucepan, bring to a boil, cover and remove from the heat.
2. Combine all of the dough ingredients. If you have a food processor with a dough hook, then knead for a couple of minutes on the slowest settng. Alternatively, mix the ingredients thoroughly with a spoon, then stretch and fold in the bowl until you have a smooth dough. Cover the dough and leave to rise for about 1 hour.
3. Oil 16 muffin cases and put them on 2 muffin trays. Set the oven to 200oC.
4. Transfer the dough to a lightly floured surface and divide  into 16 equal pieces. Very lightly turn each of the pieces in the flour, then press out to form a rough circle. Put a teaspoon of the filling mixture in the centre of each circle, and form the circle into a ball, crimping it closed with your fingers. Place each of the balls into one of your prepared muffin cases, and when the tray is full cover it with clingfilm and leave to rise in a warm place for 45 minutes.
5. Remove the clingfilm from the trays, glaze each ball with 1 dessertspoon of syrup, sprinkle about 1/4 teaspoon of brown sugar over each of them , transfer trays to oven and bake for 15-20 minutes.
6. Remove the trays from the oven, transfer the buns from their cases to a cooling rack. Pour a little more syrup over the buns before serving.