Some of you may have seen this on The Idea Room, but I tried it and am giving it a full endorsement by posting it here. You'll see that Rhett agrees.
Filling (and Topping):
1/2 c. granulated sugar
1/4 c. light brown sugar
5 t. ground cinnamon
1/2 c. whole milk (I used 2%), heated on stove top to 110 degrees (or microwaved for 40-45 seconds)
4 T. unsalted butter, (3 of them melted)
3 large egg yolks
4 1/4 c. flour, plus more if needed (can do half white and half wheat)
2 1/4 t. rapid rise yeast (1 pkg.)
1 T. sugar
1 1/2 t. salt
1. In a small bowl, combine your filling/topping ingredients. Measure out 1/4 cup of your mixture and set the rest aside.
2. In a small bowl, whisk together the milk, melted butter, and egg yolks. Then, in the bowl of your stand mixer, combine the 1/4 cup of cinnamon mixture, 1 T. sugar, yeast, flour, and salt.
3. Using your dough hook, mix on low and slowly add the milk mixture. After the dough comes together, increase your speed to medium and mix the dough until it is smooth and comes away from the sides of the bowl. Your dough should stick to the bottom of your bowl, but not too the sides. You may need to add more flour if needed.
4. Turn out your dough onto a lightly floured surface and form into a smooth round ball. Place in a greased bowl, turning to coat. Cover with plastic wrap and allow to rise for about an hour, or until dough has doubled in size. [If using instant yeast, you can skip this. Note that instant is different from rapid.]
5. Spray a 9x5 loaf pan with cooking spray. On a lightly floured surface, press dough into a 20 x 8 inch rectangle, with the short side facing you. Using a spray bottle filled with water, lightly spray the dough. Sprinkle on the cinnamon sugar mixture (reserving about 2-3 T.), leaving a 2-inch border along the top to seal. Lightly spray the cinnamon sugar with the water.
6. Adjust oven rack to middle position, and heat oven to 350 degrees. Melt 1 T. of butter and brush over top of dough. Sprinkle with remaining sugar, and bake until top is deep brown, about 45 to 60 minutes. Turn bread out and cool on wire rack.