While the dough is rising, make the filing. In a medium bowl, combine butter, brown sugar and cinnamon until mixture is homogeneous (uniform throughout). Set aside.
Spread the filling all over the dough right to the edges using greased hands or a greased spatula. This process can seem difficult but it gets easier as you spread it.
Tightly roll dough up as tight as you can, starting from the long end and place seam side down making sure to seal the edges of the dough as best you can.
Cut into 12 even rolls with sewing thread or unflavoured floss 10-12 inches long.
Place cinnamon rolls in a greased 9x13 inch baking pan in 4 rows of three, evenly spaced. Cover with plastic wrap and a warm towel and let rise again for 30-45 minutes until doubled in size and puffed up.
Preheat the oven to 375 degrees F.
Warm the heavy cream until the chill is off. Don’t make it hot, you just don’t want it cold. It should be warm to the touch.
Once the rolls have risen, remove plastic wrap and towel and pour the heavy cream over the top of the rolls, allowing it to soak down in and around the rolls.
Bake at 375 degrees for 20-22 minutes, until the rolls are lightly golden brown and the center rolls are cooked through and no longer doughy. (Note: the time will vary based on how big the rolls are, what type of pan, how close the rolls are packed, etc. They could take up to 25-27 minutes. Check the rolls at 20 minutes. If they are getting too browned, cover loosely with foil for the remaining baking time).
Allow them to cool for 5-10 minutes before frosting.