Preheat the oven to 350°F. Line a large baking sheet with parchment paper.
Prepare the Graham Cracker and Gingersnap Crumble: Break the gingersnap cookies into rough, uneven pieces, leaving some larger chunks approximately ½ to 1 inch in size. You want a mixture of larger pieces, smaller bits, and some crumbs.
Crumble the graham crackers into smaller pieces than the gingersnaps, but don't crush them into a fine powder. They should resemble coarse crumbs with some small chunks mixed in.
Combine the crumbled cookies and graham crackers in a large bowl. Add the brown sugar and salt, stirring with a fork to combine.
Pour the melted butter over the mixture and stir until everything is evenly coated.
Spread the mixture evenly onto the prepared baking sheet.
Bake for 10 minutes. Remove from the oven and allow the crumble to cool completely before assembling the trifle. Note: The crumble will remain loose rather than sticking together like a traditional pie crust. Baking gives it a toasted, buttery flavor while keeping the different cookie textures.
Prepare the Pumpkin Pie Filling: In a large mixing bowl, whisk together the dry instant vanilla pudding mixes, pumpkin pie spice, and brown sugar.
Add the cold milk and vanilla extract. Whisk until combined.
Stir in the pumpkin puree until the mixture is smooth and evenly blended.
Refrigerate the pumpkin filling until ready to assemble the trifle.
**Set aside a small portion of the cooled cookie crumble to use as a garnish just before serving.
Assemble the Trifle: Spread approximately half of the remaining crumble evenly across the bottom of a trifle bowl.
Spoon half of the pumpkin pie filling over the crumble, spreading it gently into an even layer.
Spread half of the thawed Cool Whip over the pumpkin filling.
Repeat the layers with the remaining crumble, pumpkin filling, and Cool Whip.
Cover and refrigerate until ready to serve.
Just before serving, sprinkle the reserved graham cracker and gingersnap crumble over the top.