Combine brown sugar, softened butter, and cinnamon. The butter needs to be very soft or it will be hard to spread on the dough.
Divide dough in half. Cover half of the dough with a kitchen towel. Working with half of the dough at a time, roll the first half into a 14"x12" rectangle. Spread half of the filling on the rectangle to within 1/2 inch of the edges.
Starting at the short end, roll up the dough into a log and pinch the edges to seal them closed. Place the log so the seam is on the bottom. Use dental floss or a sharp knife to cut the log into about 1 1/4' slices. (This will give you 10 slices). Or cut into twelve (1") slices. Repeat with remaining dough and filling.
Place 15 of the 1 1/4" slices in a 13x9" baking pan or dish. Place remaining 5 rolls in an 8" baking pan, 9x5" loaf pan, or small disposable baking pan.Or, place 24 (1-inch) slices in two 8-inch baking pans or dishes.
Cover with a kitchen towel and let rise in a warm place (about 85 degrees) 30 to 45 minutes or until doubled its original size. See NOTES for creating your own proofing box. If the temperature is any hotter, the buttery filling will melt and disappear to the bottom of the pan. A little is yummy. A lot missing from the middle is sad and sticky on the bottom.
Preheat oven to 375 degrees.
Uncover and bake the cinnamon rolls at 375 degrees for 20 minutes or until golden on the tops and do not spring back when touched in the middle. I would rather slightly under bake mine than over bake them if I'm in doubt of doneness. Overbaked rolls equals dry and crumbly.