To make the ice box cake:
Line an 8 by 4-inch loaf pan with plastic wrap, set aside.
To make the caramel whip cream:
In a medium-large saucepan put the sugar in a mound in the center of the pan, be sure it doesn't hit the sides. Gently add the water and corn syrup, making sure the sugar doesn't splash up on the sides of the pan. If any of the sugar is not disolved very gently stir, but make sure none of the sugar hits the sides of the pan. (All of this care to keep the sugar off the side of the pan will prevent your sugar from crystalizing while it cooks.) Cook over high heat, without stiring. When the sugar starts to color on the edges, gently stir the sugar. Until it is quite dark, it will smoke a bit.
Once the caramel is dark in color, reduce the heat and add half the cream. The caramel will sputter and sieze up, which is normal. Gently whisk the caramel until the sugar dissolves. Add the remaining cream and stir.
Strain the caramel cream into a shallow container. Cover and refrigerate until well chilled.
Using a whisk or stand mixer whip 2/3 of the chilled caramel cream until soft peaks. Reserve the remaining 1/3 of the cream for topping the cake.
Coat the bottom of the prepared pan with about a 1/4-inch-thick layer of the cream. Line the outside of the pan with the cookies. Spread a layer of the cream on each cookie and layer them together in the pan. You should end up with about 3 rows of cookies and cream.
Cover the top with more of the cream so the cookies are completely covered. Refrigerate the cake for at least 3 hours or overnight. Invert the cake onto a serving platter.
Whip the remaining 1/3 of the cream and decorate the cake as you wish.