Slice each cinnamon roll in half horizontally so that you have complete but thinner rolls. Line pie pan with half of the sliced cinnamon rolls, pressing them down slightly. The crust of the pie should cover the bottom and sides of the pan.
Combine brown sugar, flour, cinnamon, and butter into a paste in a medium mixing bowl. Spread 2/3 of filling over the crust. Sprinkle with 1 cup of pecans.
Cover filling with remaining cinnamon rolls (you may have a couple left over, depending on the size of your pie pan – tomorrow's breakfast!).
Spread remaining filling over rolls and top with remaining pecans.
Bake 30 minutes. If top crust gets too brown, cover it with aluminum foil or a pie shield.
While the pie bakes, place the icing cups on top of the oven to warm. Once the pie is done, pour icing generously over the top of the pie and wait at least 30 minutes for the icing to set and pie to cool slightly before serving.