Place the crushed pretzels in a large bowl. You want them coarsely crushed, not fine crumbs. Stir in 2 tablespoons of sugar and then work in the butter until no big chunks are left. You may need to use your hands for this step. Place in the bottom of a 9x9” baking dish. Chill until ready to use.
Wipe out the crust bowl, then add the pudding mix to the bowl. Add the milk and whisk until smooth. Add the pumpkin puree and pumpkin pie spice and mix until smooth. Carefully pour and spread over the crust. The crust isn’t solid, so you need to be careful it doesn’t get mixed into the pumpkin layer.
Place the cream cheese in the bowl and beat with a hand mixer until smooth. Add 1/2 cup sugar and vanilla and beat until combined. Fold in half of the whipped topping. Spread over pumpkin layer.
Spread the remaining whipped topping over the top of the cream cheese layer and top with grated chocolate. (To make the chocolate shavings start with a cold chocolate bar and grate it with a box grater over the top of the whipped topping.)