Blend the graham crackers in a food processor until you have a fine crumb
Whisk the graham cracker crumbs, salt and cinnamon in a medium bowl. Add melted butter and mix thoroughly
Press the crumb mixture into the bottom and up the sides of a pie dish then bake for 10-12 minutes until crust is golden brown. Allow crust to cool on a wire rack
Making the Butterscotch Filling
Whisk the egg yolks in a medium bowl then set aside
Combine the granulated sugar and ¼ cup of water together in a medium sauce pot and stir gently. Cook over medium heat without stirring for about 10 minutes, swirling the pot occasionally
The mixture will turn an amber color. Be sure to watch it closely so it doesn't burn. Remove the pot from the heat immediately when you have a dark golden brown or amber color then stir in the cream until combined. Set aside
Whisk brown sugar, milk, cornstarch, vanilla and salt in a medium sauce pot over medium heat until boiling. Turn off the heat and add the butterscotch
Add ¼ cup of the hot butterscotch mixture to the egg yolks while whisking constantly. Repeat that 4 more times then add the egg yolk mixture into the butterscotch mixture while whisking constantly
Heat the mixture over medium heat until it simmers while whisking constantly. Mixture should be slightly thickened. Remove from heat and whisk in the butter
Strain the mixture through a fine mesh strainer into a medium heat proof bowl
Pour the mixture into the cooled pie crust then refrigerate overnight
Making the Cinnamon Whipped Cream
Whisk the cool whip and cinnamon together then top fully chilled pie. Sprinkle crumbled graham cracker on top of whipped cream for garnish and serve.