reheat the oven to 350°F. Lightly spritz a 9-inch deep dish pie pan with cooking spray. Press the pie crust firmly into the pie pan. Prick the bottom of the pie crust with a fork. Place into the oven and bake for 7 minutes. Set aside.
In a medium mixing bowl, whisk together the filling ingredients. Mix until fully combined.
Pour the custard into the par-baked pie shell. Place into the oven and bake for 30 minutes.
Meanwhile, mix together ⅓ cup vanilla wafer crumbs, 1 Tbsp granulated sugar and ¼ tsp ground cinnamon. Cut the cold butter into the mixture until it resembles coarse crumbs. Mix-in the chopped pecans and English toffee bits by hand.
After baking for 30 minutes, sprinkle the pecan-crunch streusel over the top of the custard. Continue to bake for an additional 30 minutes until the custard is set when gently shaken and the pecan-crunch streusel is golden. Cover the edge of the crust with aluminum foil to prevent over-browning, if needed.
Cool the pie to room temperature then chill completely before cutting. Overnight is ideal. Serve with a dollop of fresh whipped cream, if desired.