Begin with making the chocolate filling. In a sauce pan heat the butter, chocolate and maple syrup until all melted. Stir in the rest of the filling ingredients and transfer to another bowl. Set aside for it to cool and thicken.
Weigh out the flour in a mixing bowl and scoop out 1 tablespoon of flour.
In a small bowl add the yeast, sugar and whisk in the warm water. Then add the tbsp of flour from the previous step and whisk. Set aside in a warm place until it has risen and forms bubbles.
Now add the salt, eggs, maple syrup and yeast to the flour and place it under a mixer with dough hook. Slowly add the milk while mixing at a slow speed. Continue to mix until smooth dough.
Next increase the speed to a medium speed and add the soft butter, little bits at a time. Mix until the dough is elastic, silky and smooth.
Place the dough on a large piece of floured parchment paper and roll out to a large thin rectangle shape. Spread the chocolate filling on the dough, leaving a 1cm border.
Next roll the dough as tightly as possible. Grease a sharp knife with a little vegetable oil and now cut the rolled dough with filling in half.
Take the 2 strands and plait them, securing the ends together. Carefully place the plait in a lined loaf tin and cover with a piece of clingfilm that has been brushed with vegetable oil.
Set aside in a warm place to rise for 2 hours or until doubled in size.
Preheat the oven to 175C/155C Fan/Gas Mark 4 and bake on the middle shelf of the oven for 45 – 50 minutes of until a skewer comes out clean.
Meanwhile heat the maple syrup until it bubbles and brush onto the hot babka. Cool on a wire rack for 15 minutes before removing from the tin to cool completely.