In a small pot, melt the butter with milk until very warm. Allow the mixture to cool down a bit just until it's warm to the touch. Next, sprinkle the active dry yeast over the milk and butter, stir gently and allow to sit and activate for at least 10 minutes.
While the yeast mixture is doing its thing, mix the all-purpose flour and kosher salt together in a large bowl and set aside.
In a stand mixer or handheld mixer fitted with the paddle attachment, mix the sugar with the large eggs until combined. Pour in the yeast mixture and give it a stir.
Add in half of the flour and beat on medium speed until combined followed by the rest of the flour. Switch from the paddle to the dough hook and start kneading on medium speed for 10 minutes. Helpful tip: if you find that your dough is too sticky, just add in about 1/4 cup flour.
While the dough is mixing, take out a glass bowl and either warm it in the microwave or run it under hot water so the bowl feels warm to the touch. This extra step prevents you from almost shocking the dough and keeping it nice and warm. Coat the mixing bowl in vegetable oil and place the dough in the bowl. Cover with plastic wrap and set aside in a warm spot. Let the dough rise for at least 2 hours.
Once 2 hours have passed, turn the dough onto a clean work surface and roll into a rectangle, making sure it's no longer than your loaf pan. Spread 2 tablespoons of melted butter over the dough. Next, combine 1/3 cup sugar or brown sugar and 2 tablespoons cinnamon and sprinkle the cinnamon-sugar mixture over the dough.
To fold the dough, start from the long side farthest away from you and roll the rectangle towards you until you end up with a tight roll of dough. Pinch the seam to seal and place in a greased loaf pan seam side down. Cover again with plastic wrap and allow to rise for another 2 hours.
Preheat your oven to 350 degrees F. Make an egg wash with one egg and a little milk or water. Brush that over the top of the dough and then bake for 40 minutes until golden brown. Get ready for your kitchen to smell absolutely amazing!
After the bread bakes, take it out of the loaf pan to cool down on a cooling rack before slicing.