Line pie pan with 9-inch pie crust. Add the flour, brown sugar and dash of salt and mix together, right inside the pie crust.
Pour evaporated milk over the brown sugar mixture. Do not stir. Cut the butter into several pieces and scatter it evenly over the pie. Sprinkle cinnamon over the pie.
Bake for 50-60 minutes until filling bubbles up in the middle. The filling will not completely set. Let the pie cool.
Whip the heavy cream in a medium-sized mixing bowl, until thick. Add in powdered sugar and mix on low speed to incorporate.
Spread the whipped topping over the sugar pie, or use a piping bag to add whipped cream to the pie in a decorative fashion. Sprinkle with additional cinnamon, if desired.
For the crust, you can either use a pre-formed pie shell (the kind that comes in the little foil pan ready to bake) or you can purchase a sheet of pre-made pie crust from the refrigerated section of the grocery store and press it into a 9" pie plate. It should not be pre-baked.