Preheat the oven to 350°F. Spray the bottom of a 13x9-inch baking dish with cooking spray.
First layer: Combine graham cracker crumbs, 1/2 cup pecans, melted butter, sugar and cinnamon. Mix well. Press firmly onto the bottom of the baking dish. Bake for 22-25 minutes or until golden and set. set aside to cool completely.
Second layer: Cream together cream cheese, 1 cup of powdered sugar and vanilla extract. Fold in 1/3 of the thawed whipped topping by hand. Spread over the crust and sprinkle with 1/4 cup of toffee bits. (Toffee bits are optional here).
Third layer: Whip together both boxes of pumpkin spice pudding mix with 2 cups of cold milk for 3-4 minutes until thickened. Spread over the cream cheese layer.
Fourth layer: Frost the top with the remaining whipped topping. Sprinkle with a reserved pecans and toffee bits. Toffee bits are optional.
Chill for at least 4 hours or overnight. Cut into squares for serving.
Alternate Pumpkin Layer: If you're unable to find instant pumpkin pudding mix you can adapt the pumpkin layer.Combine Two 3.4 oz boxes of instant vanilla pudding mix OR butterscotch pudding mix with 1-2 teaspoons of pumpkin pie spice (taste and adjust the amount).Whip together the vanilla pudding mix and pumpkin spice with the 2 cups whole milk called for in the recipe until thickened. Next, fold in one 15 oz can of 100% pumpkin puree by hand until fully combined. Proceed with the recipe as written for the other layers.
Notes
Crust - You could use gingersnap cookie crumbs, vanilla wafer crumbs or Biscoff cookies for the crust.
Alternate Pumpkin Layer - Don't panic if you're unable to find pumpkin spice pudding mix for this recipe. You can adapt using two boxes of instant vanilla pudding mix or butterscotch pudding mix, adding 1-2 teaspoons of pumpkin pie spice (taste and adjust the amount to your taste), and one 15 ounce can of pumpkin puree. Whip together the pudding with the milk until thickened then fold in the pumpkin puree and proceed with the recipe.
Cream Cheese - You can use Neufchatel cheese in place of full fat cream cheese.
Nuts - You could use walnuts in place of pecans for the crust and for garnishing.
Whipped Cream - You could use homemade whipped cream, if that's your preference. It's not quite as stable as Cool Whip and would need to be added to the top on the day you're planning on serving this dessert.
Homemade Whipped Cream - Use an electric mixer to whip 2 cups heavy cream with 1/4-1/3 cup granulated sugar and 1 teaspoon vanilla extract on medium-high speed until stiff peaks form. You'll need 4 cups total of sweetened whipped cream.