Step 1: Prepare the crust. In a medium bowl, combine vanilla wafer crumbs and melted butter. Mix well until crumbs are evenly moistened.
Step 2: Layer the crust. Press about half of the crumb mixture firmly into the bottom of a 3-quart trifle dish. Reserve the remaining crumbs for later layers.
Step 3: Make the cheesecake filling. In a large bowl, beat softened cream cheese, powdered sugar, and 1 teaspoon vanilla extract with an electric mixer until smooth and creamy. Gently fold in the thawed whipped topping until no streaks remain.
Step 4: Prepare the pecan pie topping. In a medium saucepan, combine chopped pecans, brown sugar, corn syrup, heavy cream, 1 teaspoon vanilla extract, and salt. Bring to a simmer over medium heat, stirring constantly, then reduce heat to low and cook for 5-7 minutes, until thickened and glossy. Remove from heat and let cool slightly.
Step 5: Assemble the trifle. Spread half of the cheesecake filling over the crust in the trifle dish. Carefully spoon half of the cooled pecan pie topping over the cheesecake layer. Repeat with another layer of the remaining crumbs, then the remaining cheesecake filling, and finally the rest of the pecan pie topping.
Step 6: Chill. Cover the trifle with plastic wrap and refrigerate for at least 2 hours, or preferably overnight, to allow the layers to set and flavors to meld.
Step 7: Garnish and serve. Before serving, you can garnish with extra chopped pecans or a dollop of whipped cream, if desired.