Grind the cookies, toffee bars, chocolate candies, and chocolate peanut butter candies separately (not too fine) in a food processor and spread them out onto 4 plates. Line a baking sheet with parchment paper or waxed paper. Using a large ice cream scoop, scoop out a big, round "boulder" of ice cream and use 2 forks to roll it in one or more of the ground toppings to cover. Carefully transfer the "boulder", with the forks, to the prepared baking sheet. Continue to make as many "boulders" as you can. Cover the baking sheet with plastic and put it in the freezer while you make the sauce.
Combine the sugar and the water in a heavy bottomed saucepan over medium heat. Give it a stir. Bring to a boil, reduce the heat and let it simmer, without stirring, until the syrup cooks down to a caramel, 10 to 15 minutes. As the sugar caramelizes, you can swirl the pan for even color. Remove from the heat. Carefully add the butter (the sugar will bubble like crazy). Then, wearing an oven mitt to protect your hand, stir. Add the cream and stir until smooth.
Serve the "boulders" with the caramel sauce.