Place both flours, salt, sugar and instant yeast in a large bowl. Mix well. You can use a standing mixer with a dough hook instead of making it by hand.

Add 150 ml (or ½ cup + 2 tbsp) of cold plant milk. Mix well with a spoon and then your hands. If the dough is not coming together and there are dry bits, add a touch more plant milk, teaspoon by teaspoon. I used the total of 160 ml (½ cup + 2 tbsp + 2 tsp) of plant milk but the exact amount depends on how absorbent your flour is so go by feel. If using a mixer, add milk gradually while running the mixer on the lowest speed, until the dough comes together.

Once the dough has stuck together, turn it out on to a work surface and knead until elastic and smooth - about 8 minutes by hand or for 3 minutes on a medium setting if using a mixer. This first phase of kneading is important as it allows the gluten to develop before you add fat, which hinders gluten development.

Form the dough into a flat disc and pile some of the vegan butter on top of it, close the dough over the butter and start kneading adding more butter cubes as you go along. If using a mixer, add butter gradually while processing on the lowest speed. Occasionally, you may need to scrape the bowl down and reposition the dough.

At this point the dough will be very slippery and messy and look like it's been ruined (see photos). It will come together again, but it needs to be patiently kneaded for about 20-25 minutes if kneading by hand or about 10 minutes if using a mixer.

Once the dough has come together again, place in a lightly oiled bowl (oil the top of the dough ball too), cover with cling film and let it proof in the fridge overnight. Alternatively, you can allow it to rise in a warm place until it doubles in size (about 2-3 hrs).

Just before you are ready to roll out your dough, melt chocolate and vegan block in a bowl suspended over a pot of barely simmering water. Sift in icing sugar, cocoa powder and salt and fold them in gently until you have a homogenous ganache.

Roll the dough out, on a lightly floured surface, until you have a large rectangle measuring approximately 40 cm / 15.5 inches by 35 cm / 13.5 inches.

Spread warm chocolate filling on the rolled out dough, leaving a 1.25 cm / 0.5 inch margin all over.

Roll the dough into a tight snake along the shortest edge. When you almost finish the roll, paint a bit of water on the bit of dough that has no filling on it and close the roll firmly (that's important). First rim 2 cm / 1 " off at both ends, then using a sharp knife, cut the snake in half lengthwise.

Arrange the two strands of dough so that the cut sides face up. Criss cross one stand over the other in the middle, then twist the two strands again and again until you get a simple braid (see photos in my post).

Tuck both ends in slighly and squeeze them with your hands gently so that they are well sealed.

Transfer to a baking tin and allow it to proof in a warm place until the dough increases in volume by about 20% - it will take about 1 hr.

Heat up the oven to 160° C / 320° F. Bake for about 45 minutes, check up on it after 35 minutes - if it's browning too much, cover the top with a piece of kitchen foil and carry on baking.

Once out of the oven, immediately glaze it with sugar syrup. Allow to cool off completely before slicing. Store in an air-tight container for about 3 days.

Combine sugar and water in a small pot. Place on a low heat and stir constantly until sugars dissolves completely. Apply to a hot babka with a pastry brush.