For the Dough:

1. In the bowl of your stand mixer fitted with the hook attachment mix 3 1/2 cups flour, salt, granulated sugar, and yeast, until combined. Turn the mixer to low and add in the milk, vanilla, and eggs one at a time until mostly combined. Add in the butter one tablespoon at a time until incorporated. Turn the mixer up to medium speed and mix for 10 minutes. Add in more dough as needed until it becomes soft, smooth, and elastic. I generally add in 4 cups total.
2. Coat a large bowl in nonstick spray or oil and place the dough into the bowl, cover, and allow to rise for 1 hour in a warm, draft-free place.

For the Filling and the Sugar Syrup:

1. In a medium bowl combine the butter, cinnamon, sugar, and salt. Set aside.
2. In a small saucepan combine the water and sugar. Bring to a boil and boil for 2 minutes, stirring frequently. Remove from the heat and set aside to cool.

Assembly:

1. Coat 2 8×4- inch loaf pans with nonstick spray. Line the pans with parchment paper, allowing the paper to overhang the ends for easy removal.
2. When the dough has risen, divide it in half. Working with one half at a time, roll out on a lightly floured surface into a 10×12- inch rectangle. Spread half of the filling onto the dough. Roll up the dough tightly from the 10- inch side into a log.
3. Cut the dough lengthwise down the middle, so the filling is exposed. Twist each half. Then twist the two halves together like a rope.
4. Place the twisted dough into one of the prepared pans. Repeat this process with the remaining dough. Cover the pans and allow to rise for 30 minutes in a warm, draft-free place.
5. Preheat oven to 350°F. Bake the loaves for 30 minutes. Remove from the oven and drizzle the sugar syrup evenly on each loaf, using all the syrup. Place back in the oven and bake for an additional 15 – 20 minutes until golden brown. To ensure the bread is baked it will reach an internal temperature of 190°F.
6. Place a wire cooling rack on a baking sheet and remove the bread from the pans using the parchment paper, transferring them to the wire rack to cool. Sugar syrup will drip from the bottom of the bread as it cools.