How to Make It
Preheat the oven to 350°. In a medium bowl, combine 4 tablespoons of the butter and 1/4 cup of the brown sugar with the flour and pinch into moist crumbs. Stir in the pecans.
In a large bowl, using an electric mixer, beat the remaining stick of butter and 3/4 cup of brown sugar at medium speed until light and fluffy, about 1 minute. Beat in the pumpkin puree, egg yolks, cornstarch, cinnamon, nutmeg, cloves and salt, then beat in the milk and bourbon.
In a stainless steel bowl, using clean beaters, beat the egg whites until stiff but not dry, then fold into the pumpkin mixture until no white streaks remain.
Pour the custard into the baked Flaky Pie Shell. Sprinkle the pecan streusel on top. Bake the pie in the middle of the oven for 1 hour, or until risen and golden and a toothpick inserted in the center comes out with only a few moist crumbs attached. Let cool and serve.
Sweetened whipped cream.