Make the crust: Pulse the flour, granulated sugar and salt in a food processor to combine. Add the butter and pulse until it is in pea-size pieces. Whisk the egg yolk with 1/4 cup ice water; add 2 tablespoons to the food processor and pulse a couple of times. Add the remaining egg mixture and pulse a few more times until the dough just comes together but is still crumbly. Turn out onto a piece of plastic wrap; shape into a disk and wrap. Refrigerate until firm, at least 1 hour or overnight.
Put a baking sheet on the middle oven rack and preheat to 425 degrees F for 30 minutes. Meanwhile, roll out the dough into a 12-inch round on a lightly floured surface. Ease the dough into a 9-inch pie plate. Fold the overhanging dough under itself and crimp with your fingers or a fork. Refrigerate until firm, about 30 minutes.
Meanwhile, make the filling: Whisk the eggs, brown sugar, corn syrup, melted butter, vanilla and butter extracts, lemon juice, salt, pecans and toffee bits in a large bowl until combined. Pour the filling into the chilled crust. Transfer the pie to the hot baking sheet and reduce the oven temperature to 350 degrees F. Bake until the crust is deep golden and the filling is set around the edge but still jiggly in the center, 55 minutes to 1 hour. (Tent the crust with foil if it browns too quickly.) Transfer to a rack and let cool completely.