To par bake the crust: Preheat the oven to 375 F. Cover the pie crust with foil and add pie weights. Bake for 30 minutes.
To brown the butter: while the crust is par-baking, brown the butter by adding the butter to a saucepan and cooking until it first melts, then bubbles and spits, then goes quiet and you see brown bits at the bottom. Remove from heat as soon as it is done by pouring it into a heat-proof container.
To make the filling: whisk together the brown butter and sugar swiftly for 30 seconds, you want the mixture to cool down and for the sugar to begin to melt into the butter. Add the salt and vanilla and whisk. Add the eggs and whisk for a full minute to allow the ingredients to emulsify. Add the cocoa, flour, pecans and chopped chocolate and stir to combine. Pour the filling into the half-baked pie shell, lower the oven temperature to 350 F and bake for 30 minutes.
To make the meringue topping: Set egg whites in the bowl of a stand mixer. In a pot, combine the water and sugar and attach a candy thermometer. Cook until the temperature registers 250 F the ‘candy’ stage. While it’s cooking, begin whipping the egg whites with the salt until frothy. Once the sugar syrup has reached 250 F, with the mixer on, pour the syrup slowly onto the egg whites as they whip. Add the vanilla, also while the mixer is on. Continue whipping until the meringue glossy and holds stiff peaks. Sift the cocoa over the meringue and using a rubber spatula, carefully fold it into the whipped meringue. Dollop it onto the cooled pie.
To broil the meringue: if you don’t have a kitchen torch, you can preheat your oven to a high broil and set the pie under it for about 2 minutes, keeping a watchful eye on it.
Serving and storing: the pie can be stored in the fridge for 3 days. For even slices, run a knife under hot water and dry it, then slice through. Wipe the knife between slicing for clean cuts.