Preheat oven to 350℉.
To make the crust, in a large bowl add the graham cracker crumbs and brown sugar. Add the melted butter and mix well.
Press the mixture up the sides and in the bottom of an ungreased 9-inch pie plate. Bake for 7 minutes. Remove from oven and set aside.
In a large bowl, combine the sweetened condensed milk, egg yolks, and lime juice with a whisk. Whisk until smooth. Pour into pie crust and bake for 15 minutes. Remove from oven and cool while making the meringue.
Lower the oven to 325℉.
To make the meringue, using an electric mixer, whisk the egg whites and salt until soft peaks form. Gradually add the marshmallow cream until the mixture is smooth and stiff peaks form.
Top the pie with the meringue, using the knife or spatula to form peaks all over the pie. Bake until light brown. Cool completely then refrigerate for several hours, until cool, before serving.