Stir together the cookie crumbs and butter until thoroughly combined.
Press firmly and evenly into the bottom and up the sides of a 9-inch pie plate. Place in the freezer while you make the filling.**
To make the filling:
Stir together the gelatin and cold water, and allow to stand for 1 minute.
Heat 1/2 cup cream in the microwave for 45 seconds. Pour over the gelatin and whisk until the gelatin has dissolved. Refrigerate for 5 minutes.
Place the remaining 2 & 1/2 cups cream, brown sugar, and vanilla in a large, cold mixing bowl. Using an electric mixer with a whisk attachment, beat at medium-high speed until the cream begins to thicken.
Gradually add the gelatin mixture and continue beating until medium peaks form.
Transfer the whipped cream to the prepared crust, and spread evenly. Refrigerate at least 6 hours.
Drizzle with caramel and sprinkle with a salt before serving.
Notes
*Substitute your favorite crunchy cookie for the crust - graham crackers, chocolate wafers, etc. If you use a different kind, I recommend measuring by volume (1 & 1/2 cups), as the weights of different cookies will vary.
**As a general rule, I prefer to bake cookie crusts at 350°F for about 10 minutes just to make them a bit sturdier. But freezing the crust is a great alternative to make this a truly no-bake dessert.