Heat oven to 375°F.
Line a 10-inch, deep-dish (2 inches) tart pan with the piecrust. Be sure to press the dough into the sides and that there are no cracks or holes in the dough. Once assembled, chill the crust while you make the filling.
Combine the sugar, cocoa, salt, eggs, evaporated milk, butter, and vanilla in your blender carafe and blend until smooth, about 1 minute. Pour the filling into the prepared piecrust.
Bake until the edges are set but the middle still has a bit of wobble to it, 30 to 35 minutes. Cool for at least 1 hour before beginning the meringue.
To make the meringue, combine the sugar, corn syrup, and 2 fluid ounces (59 milliliters) water in a small saucepan. Cover and place over medium heat. Once boiling, uncover and bring the mixture to 240°F.
While the sugar syrup is cooking, whisk the egg whites and vanilla to medium peaks with a stand mixer fitted with the whisk attachment on high speed, 2 to 3 minutes.
With the mixer on low, pour the hot sugar syrup into the egg whites. Return the mixer to high speed after all of the sugar syrup has been added and whip to stiff peaks.
Fold the chopped pecans into the finished meringue. Dollop the finished meringue onto the cooled pie and use a blowtorch to brown the meringue before serving.