Step 1: Prepare the Crust

1. Preheat the oven to 350°F (175°C).
2. In a bowl, mix graham cracker crumbs, sugar, and melted butter until the texture resembles wet sand.
3. Press the mixture firmly into the bottom and sides of a 9-inch pie dish.
4. Bake for 8-10 minutes, then let it cool while preparing the filling.

Step 2: Make the Custard

1. In a medium saucepan, heat the milk over medium heat until it is warm but not boiling.
2. In a separate bowl, whisk together sugar, eggs, vanilla extract, cinnamon, salt, and cornstarch until smooth.
3. Slowly add a small amount of warm milk to the egg mixture, whisking continuously to temper the eggs.
4. Pour the egg mixture back into the saucepan with the remaining milk, stirring constantly.
5. Cook over low heat, stirring until the mixture thickens to a pudding-like consistency (about 5-7 minutes).
6. Remove from heat and let the custard cool slightly.

Step 3: Assemble and Bake

1. Pour the custard into the prepared pie crust, smoothing the top with a spatula.
2. Bake at 325°F (163°C) for about 30-35 minutes, or until the center is set but still slightly jiggly.
3. Let the pie cool completely before refrigerating for at least 2 hours to set.

Step 4: Serve and Enjoy

1. Dust with extra cinnamon and serve with whipped cream or fresh berries for a festive touch.