For the brioche dough:

1. Heat the milk to 110 degrees F and stir in yeast and sugar. If using active dry yeast, allow to sit for 15 minutes. If using instant yeast, simply move on to the next step.
2. Mix the eggs and vanilla into the milk yeast mixture.
3. Combine flour, spices, and salt together in the bowl of a stand mixer fitted with a dough hook.
4. Pour the wet ingredients into the flour and mix on low-medium speed for about 3 minutes, or until it forms a ball around the hook.
5. Add in one piece of butter at a time, allowing it to fully incorporate before adding the next.
6. Once all of the butter is incorporated, turn the mixer up to medium-high speed and mix for 6-8 minutes. To check if the dough is ready, tear off a small piece and carefully spread it out to see if you can see the light through it without it tearing. If it tears, mix for another minute and check again.
7. Once the dough is ready, transfer it to a lightly greased bowl, cover, and allow to proof overnight in the fridge. Alternatively, you can let the dough rise in a warm place for about 1 hour or until doubled in size.

For assembly:

1. After the first rise, punch the dough down and transfer it to a lightly floured surface.
2. Spread the dough out slightly and add the chocolate chips to the center.
3. Fold the edges of the dough over the chocolate chips and knead gently until the chocolate is evenly distributed throughout the dough.
4. Divide the dough into 12 equally sized balls. Mine measured out to be 67g each.
5. To shape each ball, flatten it out then bring the edges into the center and seal it. Turn the ball over and roll into a smooth ball.
6. Place each ball in a 9x13 pan lined with parchment paper.
7. Cover and allow to rise for about 30 minutes.
8. Meanwhile, preheat the oven to 350 degrees F and make the cross piping.

For the crosses:

1. Combine the flour and water in a small bowl, and mix until smooth.
2. Transfer to a piping bag.
3. Once the buns have proofed, snip the end of the piping bag and pipe one line across all of the buns in one motion each way.
4. Bake the buns for about 20-25 minutes until golden and reaches 190 degrees F on an internal thermometer.

For the sugar syrup:

1. While the buns are baking, combine the water and sugar in a small saucepan.
2. Boil for 2 minutes and set aside until the buns are done.
3. Once the buns come out of the oven, immediately brush the sugar syrup on top.