Heat oven to 350°F.
Make crust: Combine cracker crumbs, 2 tbsp granulated sugar, and 1/4 tsp salt. Add the melted butter and mix to moisten dry ingredients. Press onto bottom and up sides of a 9" pie pan Bake until the edges of the crust are beginning to brown, 8-10 minute.
Make filling: Melt the butter in a small saucepan over medium heat. Once melted, swirl the pan until the butter begins to brown, 2-3 minutes more. Remove from heat.
In the top half of a double boiler, combine the brown sugar, flour, cornstarch, and 1/2 tsp salt. Stir in the browned butter, milk, and egg yolks until fully incorporated. Cook mixture over simmering water, whisking until the mixture thickens and coats the back of a sppon, about 8 minutes. Pour the pudding mixture into the prepared crust. Lay a piece of plastic wrap over the top of the pie to prevent a skin from forming. Refrigerate while you make the meringue.
Make the meringue: With an electric mixer, beat the egg whites and cream of tartar until frothy. Add the salt and beat until soft peaks form. Add the sugar, 1 tbsp at a time, beating until incorporated. Continue to beat until glossy peaks form, about 4 minutes. Beat in the vanilla.
Remove the plastic from the pudding. Spoon some of the meringue onto the edge of the pudding, spreading it right up to and touching the crust to create a seal. Spoon the rest of the meringue into the center, and using the back of a spoon, spread to cover the entire top.
Bake until the meringue is golden brown, 10 to 15 minutes. Let stand for at least 1 hour before serving.