For the dough, in a stand mixer fitted with the dough hook, combine the water, butter, sugar and yeast. Mix and let rest until foamy, 1 to 2 minutes.
Add the salt and flour and mix until the dough comes together to form a shaggy ball that clears the sides of the bowl. Add additional flour a few tablespoons at a time, if needed (but don't over flour the dough). The dough should be soft and slightly sticky.
Knead the dough in the mixer on medium speed for 4 to 5 minutes until the dough is smooth. Cover the mixer and let the dough rise until doubled (or transfer the dough to a lightly greased bowl for rising).
In a medium bowl or shallow dish, like a pie plate, combine the brown sugar, granulated sugar, and cinnamon and mix until well-combined. Measure out 1/2 cup of the mixture and set aside.
Grease two 8 1/2-inch by 4 1/2-inch loaf pans generously with cooking spray and set aside.
Gently punch down the dough and divide into two equal pieces. Pat each piece into a thick rectangle, about 9 inches by 5 inches. Cut each rectangle into five thick strips.
Working with one set of five strips at a time, dip each strip in the melted butter and then roll in the cinnamon-sugar mixture until evenly coated. Place the strip at the top (of the short side) in one of the prepared loaf pans and repeat with the remaining four strips, tucking each strip in to fit in an even, single layer.
Repeat with the remaining strips for the second loaf pan. If there is extra cinnamon sugar mixture, sprinkle it evenly over the loaves.
Cover the pans and let the bread rise until noticeably puffy and the dough has risen to almost reach the top of the pan.
While the bread rises, ensure an oven rack is in the center position and preheat the oven to 350 degrees F. If you are worried about cinnamon-sugar dripping onto your oven rack/floor, place the bread pans on a sheet pan before baking (the bread doesn't overflow/leak in my oven, but depending on how high the bread rises and/or your elevation, it may be a helpful word of caution).
Bake the bread for 30 to 32 minutes until golden and baked through (an instant-read thermometer inserted in the thickest part of the bread should register 190 to 200 degrees F.)
While the bread bakes, mix the reserved cinnamon-sugar mixture with the 4 tablespoons melted butter until well combined.
Remove the bread from the oven, keep it in the bread pan, and immediately brush the tops of each loaf evenly with the cinnamon-sugar/butter mixture.
Let the bread cool for 10 to 15 minutes in the pan. Run a sharp, thin knife around the edges and gently turn the bread out onto a plate, serving tray or cutting board (so that it is right side up).
For the glaze, whisk together the powdered sugar and milk until no lumps remain. If needed, add additional powdered sugar or milk to achieve a thick drizzling consistency. Drizzle the glaze over the warm bread.
Serve warm or at room temperature.
Notes
Butter: I use salted butter. If using unsalted butter, increase the salt in the recipe as needed (usually about 1/4 teaspoon per stick of butter).