In a large bowl of a stand mixer using the dough hook attachment. Mix the starter, sugar and 200g of the water together, on low speed, until combined. Set aside.

Next, take the 100g of remaining water, and shortening and heat in a small saucepan until the shortening is dissolved. Cool until no warmer than 85 degrees.

Once that mixture is cooled add to the bowl, the shortening/water, flour and mix with the dough hook attachment on low until dough just begins to form (1 minute). It should still be shaggy.

Autolyse (let rest) covered with a tea towel for 45 minutes.

Next add the egg and kosher salt to the bowl and knead/mix for 10 minutes on the lowest setting. Scraping the sides of the bowl as needed.

Then move to a bowl and do an envelope fold and flip over.

Let sit for 30-50 minutes, then stretch and fold in four directions. Repeat 4 times.

Cover and let sit at room temp for one hour.

Place in refrigerator over night.

Remove dough from bowl and roll out to half inch thick rectangle.

In a small bowl, combine 1/4 cup butter, 1/2 cup brown sugar and 1 Tbsp cinnamon.

Spread mixture evenly over the dough.

Starting from the long side, roll the dough to form a log. Pinch the open edge to make it hold its shape.

Cut the dough roll into 12 slices. Place the slices flat in a 9x13 pan. Cover and let rise 1 hour.

Preheat oven to 425. Bake for ten minutes, then reduce heat to 325 and continue baking for 32 minutes.

Let cool in the pan while you prepare the sauce.

In a sauce pan, combine sweetened condensed milk, 1/2 cup brown sugar, 1/4 cup sugar, and 1/2 cup milk. Heat until sugar are dissolved and the mixture begins to caramelize.