Place a sheet pan in the oven and preheat to 375 degrees F.
Whisk together the cornstarch with 2 tablespoons cold water in a small bowl to form a slurry. In a food processor, blend together the eggs, yolks, brown sugar, vinegar, vanilla, 1 stick butter, 1/3 cup maple syrup, 1/3 cup corn syrup, 1 teaspoon salt, 1/2 cup heavy cream and the cornstarch slurry. Once smooth, add 1 1/2 cups pecans and pulse in 5-second increments until they are chopped into small pieces.
Pour pie filling into shell and place on preheated sheet pan. Bake until the very center of the pie is barely set, 40 to 45 minutes.
Roughly chop the remaining 2 1/2 cups pecans. Heat a large skillet over medium heat and melt the remaining 5 tablespoons butter, then add 1/4 cup maple syrup and 3 tablespoons corn syrup. Cook, stirring with a wooden spoon, until bubbly, then stir in the remaining 1/2 cup cream and 3/4 teaspoon salt. Reduce heat to low, stir in pecans, and continue cooking, stirring, for about 2 minutes. Pile pecans onto pie and return to oven until you can smell the pecans toasting, about 5 minutes. Allow to cool to room temperature before serving.