Heat the oven to 425°F (220°C) for the crust’s first bake. The oven should reach temperature before the pastry goes in.
Fit an 11-inch round of rolled dough into your pie pan, press away trapped air, dock the bottom and sides with a fork, and add parchment filled with pie weights or dried beans. The dough should sit against the pan without air bubbles, with the weights supporting its shape.
Give the weighted shell 15 minutes in the oven, lower the heat to 350°F (180°C), lift out the parchment and weights, and bake uncovered for another 5 minutes before setting it aside to cool completely. Keep the oven on while the exposed pastry finishes cooling.
Distribute the cornstarch throughout the filling sugar with a whisk in a medium saucepan, keeping the pan off the heat. The dry mixture should look uniform, without pockets of starch.
Whisk the cream and filling butter into the saucepan over medium heat, stirring continuously, then maintain the boil for 1 minute. Look for heavy bubbles breaking through the thickened cream and ribbons trailing behind the whisk.
Take the saucepan off the burner, incorporate the vanilla and salt, and spread the hot filling evenly in the cooled shell with a spoon or spatula. The surface should look smooth rather than mounded in the center.
Distribute the melted topping butter across the filling, then mix the topping sugar with the cinnamon and scatter it over the butter. A fairly even coating will help the surface brown consistently.
Bake the filled pie on the middle rack at 350°F (180°C) for 20 to 25 minutes. The outer filling should look set while the center retains a gentle, gelatin-like wobble.
Switch to broil and watch the surface continuously for up to 1 minute, stopping when the sugar browns and crystallizes. The topping should look golden and bubbling, not dark or scorched.
Let the pie cool to room temperature, then refrigerate it until thoroughly chilled and ready to cut. The filling should feel firm and cold rather than loose and warm.