How to Make It
Make the piecrust Preheat the oven to 350°. Spread the pecans on a baking sheet and toast for about 8 minutes, until fragrant and lightly browned. Let cool.
In a food processor, pulse 1/2 cup of the pecans until finely ground. Add the flour and salt and pulse to mix. Add the butter and pulse until pea-size pieces form. Add the ice water and pulse until a dough starts to come together. Transfer the dough into a 9-inch round fluted tart pan with a removable bottom and press it evenly over the bottom and up the side. Prick the piecrust all over with a fork, then freeze it for 30 minutes.
Preheat the oven to 375°. Put the piecrust on a large baking sheet and bake for about 35 minutes, until the edge is lightly browned and the crust is firm. Let cool completely.
Meanwhile, make the filling In a small saucepan, bring the milk and 1/2 cup of the cream to a simmer over medium heat. Remove from the heat. In a medium saucepan, melt the butter over moderately high heat. Add the brown sugar and cook, whisking constantly, until the mixture is bubbling and smooth, about 2 minutes. Remove from the heat and gradually whisk in the milk mixture.
In a medium bowl, beat the eggs with the cornstarch and salt. Very gradually whisk in 1/2 cup of the milk mixture. Scrape the mixture into the medium saucepan and cook over moderate heat, stirring constantly, until very thick, about 7 minutes. Strain the pudding into a medium bowl and stir in the Scotch and vanilla. Let cool slightly, then press a piece of plastic directly on the surface and refrigerate until well chilled, at least 4 hours or overnight.
Scrape the butterscotch filling into the piecrust and smooth the top. In a large bowl, using a hand mixer, beat the remaining 1 cup of cream until stiff peaks form. Mound the whipped cream on the pie and garnish with turbinado sugar and the remaining 1 tablespoon of pecans. Cut the pie into wedges and serve.
Use the bottom of a metal measuring cup to help press the dough into an even layer in the tart pan.