Create the Graham Cracker Pecan Crust
Preheat your oven to 350°F (175°C). In a food processor, pulse the graham crackers and pecans into fine crumbs. Transfer to a bowl and mix with granulated sugar and melted butter until well combined. Press the mixture firmly and evenly into the bottom of a 9×13-inch baking dish. Bake for 10 minutes, then let it cool completely on a wire rack.

Prepare the Stabilized Homemade Whipped Topping
In a small, microwave-safe bowl, sprinkle the gelatin over the cold water and let it sit for 5 minutes to bloom. Microwave for 10-15 seconds, or until the gelatin is fully dissolved, then set aside to cool slightly. In a large mixing bowl, use an electric mixer to beat the very cold heavy cream, powdered sugar, and vanilla extract on medium-high speed until soft peaks form. With the mixer running on low, slowly stream in the cooled gelatin mixture. Increase the speed to high and beat until stiff peaks form.

Mix the Smooth Cheesecake Layer
In a separate large bowl, beat the softened cream cheese with an electric mixer until completely smooth and free of lumps. Add the powdered sugar and milk, and beat until combined. Gently fold in 1 ½ cups of the prepared whipped topping until just incorporated. Spread this cheesecake mixture evenly over the cooled crust.

Whisk Together the Pumpkin Fluff
In another bowl, whisk together the instant vanilla pudding mix and the cold milk for about 2 minutes, until it begins to thicken. Whisk in the pumpkin puree and all the spices (cinnamon, nutmeg, cloves, and ginger) until smooth. Gently fold in 1 cup of the whipped topping. Carefully spread this pumpkin layer over the cheesecake layer.

Assemble, Top, and Chill to Perfection
Spread the remaining whipped topping evenly over the pumpkin fluff layer. Sprinkle the toffee bits all over the top. Cover the dish with plastic wrap and refrigerate for at least 6 hours, or preferably overnight, to allow the layers to set completely before slicing and serving.