In a large bowl, mix the ingredients for the sponge together. Now sprinkle the all-purpose flour, bread flour, and salt on top so that all the starter is covered. Let this sit for 20 minutes.

In a small bowl, combine all the ingredients for the cinnamon sugar filling with a fork and set aside.

In another large mixing bowl, cream the butter (final dough) with a paddle attachment until it’s light and fluffy, about 2 minutes. Add the lemon zest, cinnamon, chai masala, and brown sugar and cream for another 2 minutes on medium high. Now add your eggs one at a time, mixing in between and scraping down the sides of the bowl. According to Joy the Baker, this will not mix well, it will look coagulated this is ok because there is more egg than butter.

Now add your sponge mixture from Step 1 into the mixer with the butter and mix with the paddle attachment for 1 minute on medium high. Then swap out the paddle attachment with the dough hook and mix at low-speed for 5 minutes. Take the dough off the hook and put it in a greased bowl and cover it with plastic wrap, tucking in the sides so that no air can get to the dough. Let this rest for 1.5 hours.

Take the dough and flatten the dough out into a rectangle. Fold it in half three times and put it back in the greased bowl and cover with plastic wrap. Let this rest for 30 minutes.

Take the dough out and roll out into a 12 inch by 15 inch rectangle. Spread the cinnamon sugar filling on top. Now starting with the long side, tightly roll up the dough. Pinch the edges together when your done to seal the roll. Let this sit for 5 minutes and start pre-heating your oven at 375 F.