1. Preheat oven to 350 degrees F. Melt 4 tablespoons of butter in the bottom of a pie plate. Add the brown sugar to the butter and stir to combine. Cover the bottom evenly with butter/sugar mixture.
2. Unroll crescent dough and pinch seams together to create one big sheet. Spread with remaining softened butter. Combine white sugar and cinnamon and sprinkle over the buttered dough. Roll the dough back up into a log, and cut into 8 cinnamon rolls. Place rolls in prepared pie plate. Sprinkle with any remaining cinnamon sugar.
3. Bake at 350 for 20 minutes. Top with cinnamon roll icing (recipe follows) and serve warm. Store leftover cinnamon buns at room temperature.

FOR THE CINNAMON ROLL ICING

1. With a fork, stir together sugar, cream, and vanilla until smooth and pourable. Add one tablespoon of milk if needed to thin. If using milk and butter instead of cream, heat the milk and butter in the microwave to melt the butter, then add to the sugar and stir in vanilla.