Step 1: Prepare the Crust

• Preheat your oven to 350°F (175°C). Grease a 9-inch pie dish.

• In a medium bowl, combine graham cracker crumbs, sugar, and cinnamon (if using).

• Stir in melted butter until mixture resembles wet sand.

• Press mixture firmly into the bottom and up the sides of the pie dish.

• Bake crust for 8-10 minutes until lightly golden. Remove and cool.

Step 2: Make the Butterscotch Filling

• In a medium saucepan over medium heat, whisk together brown sugar, flour, and salt.

• Slowly add milk, whisking constantly to prevent lumps.

• Cook, stirring occasionally, until mixture thickens and begins to boil.

Step 3: Temper the Egg Yolks

• Gradually add a small amount of hot mixture into beaten egg yolks, whisking continuously.

• Slowly pour egg yolk mixture back into the saucepan, whisking constantly.

Step 4: Finish Cooking the Filling

• Cook for another 2–3 minutes, stirring until filling is smooth and thick.

• Remove from heat; stir in butter and vanilla until butter melts and filling is glossy.

Step 5: Assemble the Pie

• Pour filling into cooled graham cracker crust.

• Smooth top with a spatula.

Step 6: Chill and Serve

• Let pie cool at room temperature for about 30 minutes.

• Refrigerate for at least 3 hours until fully set.

• Top with whipped cream before serving, if desired.