Prepare the pie crust according to your preferred method and bake until golden.

In a saucepan, melt the butter over medium heat.

Whisk in the flour and cook for 1-2 minutes to form a roux.

Gradually add the brown sugar, milk, and salt, whisking constantly until the mixture thickens and comes to a boil.

In a separate bowl, beat the egg yolks.

Slowly temper the egg yolks by adding a small amount of the hot mixture, then whisk the tempered yolks back into the saucepan.

Continue to cook for an additional 2 minutes, then remove from heat.

Stir in the vanilla extract.

Pour the filling into the prepared pie crust.

Prepare the meringue by beating the egg whites until soft peaks form.

Gradually add sugar and continue to beat until stiff peaks form.

Spread the meringue over the pie, sealing the edges.

Bake in a preheated oven at 350°F (175°C) until the meringue is golden brown, about 15 minutes.

Cool before serving.