Bake your single layer pie crust in a 9-inch pie dish according to package or recipe directions.
Add the brown sugar, heavy cream, and butter into a medium saucepot and cook over medium-low heat, whisking immediately and constantly so the sugar doesn’t burn.
Once the butter melts it will become smooth, stirring occasionally, bring it to a boil, reduce to a simmer and simmer for 2 minutes until slightly thickened. Take off the heat.
Reserve 2 tablespoons of the milk and whisk the remaining milk into the pot, set aside.
Place a fine-mesh strainer over a large bowl, set aside.
In a bowl, whisk together the cornstarch, egg yolks, and salt until smooth. Stream the egg mixture into the pot while whisking.
Place the pot back on the stove over medium-low heat, whisking constantly so it doesn’t scorch on the bottom. The mixture will thicken to a thick pudding-like consistency.
Immediately pour the custard over the strainer and bowl, you will need to do this a little at a time, you will need to use a spatula to press the custard through the strainer. Don’t forget to scrape the custard off the bottom of the strainer when you are done.
Whisk the vanilla into the custard. Pour this mixture into the baked pie crust and smooth out the top. Let cool to room temperature.
Cover with plastic wrap and place in the fridge for at least 6 hours until set or overnight is best. Serve with whipped cream and your favorite toppings.