Preheat oven to 350°F and grease a 9 x 13-inch baking dish lightly with butter.
In a large bowl, beat softened butter, brown sugar, salt, and cinnamon until smooth.
Gradually mix in flour at low speed until incorporated, then stir in toasted chopped pecans.
Spread the dough evenly into the prepared dish to form the base; bake for 18-20 minutes until light golden.
Remove from oven and let the base cool completely.
Beat cream cheese and powdered sugar until smooth and creamy, then gently fold in 1 1/2 cups whipped topping and vanilla extract.
Spread the cream cheese mixture evenly over the cooled shortbread base and freeze for 10 minutes to set.
Whisk caramel instant pudding mix with cold milk until thickened, then spread over the cream cheese layer.
Place the dish in the freezer for 5-10 minutes to set the pudding layer further.
Spread the remaining 3/4 cup whipped topping evenly over the pudding layer and refrigerate.
In a skillet over medium heat, combine chopped pecans, brown sugar, and cinnamon; stir constantly for 5 minutes until sugar melts and coats pecans.
Transfer candied pecans to parchment paper and let cool completely, then break into small clusters.
Sprinkle candied pecans over the dessert, drizzle caramel sauce on top, and refrigerate for 3-4 hours before slicing.