Combine the graham cracker crumbs, brown sugar, and melted butter until mixture is moist. Press into a 9-inch pie plate.
Bake the crust in the oven until toasted, about 10-12 minutes.
Meanwhile, beat softened cream cheese, ¾ cup powdered sugar, peanut butter, and vanilla extract together in a large bowl until soft and light. If using a stand mixer, use the paddle attachment.
In a separate bowl, make the whipped cream. Using the whisk attachment of your mixer or a balloon whisk, whisk heavy cream until thick. Add remaining ¼ cup of powdered sugar and whisk until stiff peaks form.
Add 2 cups of whipped cream to the peanut butter mixture and beat until combined and creamy. Reserve the remaining 2 cups of whipped cream in a covered bowl in the refrigerator.
Smooth the peanut butter filling into the baked graham cracker crust with a spatula. Chill in the refrigerator until set, about 3-4 hours.
Once the pie is set, spoon reserved whipped cream on top and spread to cover. Sprinkle shaved chocolate over top. Store in the refrigerator for up to 5 days.