Preheat the oven to 325 degrees.

Finely crush the cookies in a food processor. Add the 6 tablespoons melted butter. Mix well. Pack firmly into a 9-inch pie plate. Bake for 10 minutes. Let cool. Leave oven on.

Combine the bananas, 4 tablespoons melted butter, and brown sugar in a baking dish and bake for 30 minutes.

Combine the buttermilk, sugar, eggs, flour, lemon juice, vanilla, and nutmeg in a mixing bowl. Whisk to combine.

When the bananas are done, stir into the buttermilk mixture, including all the juices. Pour mixture into pie crust and bake for 60 minutes or until the filling is set. Keep the oven on.

Make the meringue filling by combining the egg whites and cream of tartar in the bowl of an electric mixer fitted with the whisk attachment. Beat on low speed until foamy. Increase speed to high and add the sugar, 1 tablespoon at a time. Continue to beat until stiff peaks form, about 8 minutes.

Using the back of a spoon, spread the topping over the hot pie, making sure to cover the edges of the pie. Use the back of the spoon to pull the meringue into peaks all over the pie. Put the pie back in the oven and cook for 12-15 minutes or until golden brown.