Step 1: Make the Crust

1. Crush biscuits into fine crumbs using a food processor or rolling pin.
2. Combine with melted butter and brown sugar until the texture resembles wet sand.
3. Press evenly into the bottom of a 9x13-inch pan. Chill while preparing the filling.

Step 2: Prepare the Nut Layer

1. In a saucepan over medium heat, melt butter and stir in brown sugar.
2. Cook for 2-3 minutes until bubbling.
3. Stir in heavy cream, vanilla, and a pinch of salt.
4. Add chopped pecans and stir to coat.
5. Let cool slightly, then spread evenly over the chilled crust.

Step 3: Whip the Cream Layer

1. Dissolve gelatin in water and let bloom for 5 minutes.
2. Beat mascarpone with powdered sugar until smooth.
3. In a separate bowl, whip heavy cream until soft peaks form.
4. Gently fold whipped cream into mascarpone mixture.
5. Add the gelatin and mix until smooth.
6. Spread over the nut layer. Chill for at least 4 hours or overnight.

Step 4: Make the Caramel Topping

1. In a dry saucepan, melt sugar over medium heat, swirling occasionally.
2. Once amber-colored, carefully add butter, stirring constantly.
3. Slowly pour in cream, whisking until smooth.
4. Let cool before drizzling.

Step 5: Assemble and Garnish

1. Once the dessert is set, drizzle caramel sauce generously over the top.
2. Garnish with whole pecans and, if desired, extra cookie crumbs or biscuits.
3. Chill again briefly before slicing.