Make the crust. Mix the dry ingredients together so it is all evenly distributed.
Drizzle in the melted butter, then stir well.
Press the crumbs into a 9-inch pie pan. Start with the sides and edges, then the bottom of the plate. Freeze until needed.
Make the filling. In a small bowl, stir together the cornstarch and ⅓ cup of the heavy cream together until well-combined.
Add in the milk, sugar, sea salt. and the remaining heavy cream in a large saucepan. Heat on medium until it is steaming and is very hot. Stir well, scraping the bottom and sides to prevent burning.
Stir the cornstarch mixture into the egg yolks.
Take 1 cup of the hot cream and milk mixture and slowly drizzle into the egg yolks while whisking the egg yolks.
Slowly add the egg mixture into the saucepan and whisk constantly until the mixture thickens.
Turn off the heat once the mixture begins to thicken to a pudding consistency.
Add the chocolate and butter. Stir until the butter and chocolate are melted and well-combined.
Stir in the vanilla.
Strain the mixture through a fine-mesh strainer into a bowl.
Give the mixture a quick whisk. Cover the top of the bowl with plastic wrap. Make sure the plastic wrap directly touches the filling. This helps to prevent skin from forming.
Allow to cool completely.
Make the meringue. Freshly wash your heatproof mixing bowl and whisk, rub down with lemon juice and dry.
Add the egg whites and the granulated sugar into your clean mixing bowl. Place the bowl over a small saucepan with an inch of boiling water to create a double boiler.
Whisk the egg whites constantly for about 5 minutes, or until the granulated sugar has fully dissolved.
Take your mixing bowl off the smaller saucepan and beat the egg whites to soft peaks.
Add in the cream of tartar, then continue to beat until it reaches stiff peaks.
Beat in the vanilla.
Assemble your pie. Pour the chocolate filling into the pie pan. Spread smooth on top. Top with the meringue. Use a kitchen torch to toast the meringue. If you do not have a kitchen torn, you may use your oven broiler, just remember you will need to chill the pie to re-set the filling.
Serve. Please see notes for my tip on getting clean slices.
*Experiment with different chocolate if you'd like! Milk chocolate is too sweet to use in this pie along, but if you aren't a huge fan of dark chocolate, you can use a mix of milk and dark or milk and semi-sweet. Tip: To ensure clean slices I recommend chilling the pie for at least an hour after you've assembled. When cutting, wipe your knife clean after each slice.