Place about a third of the cookies in a zip-lock plastic bag, seal bag, and roll with a rolling pin until cookies are finely crushed; pour into a 9-inch cheesecake pan with removable rim (at least 2 in. tall). Repeat to crush remaining cookies (you need 1 3/4 cups total) and pour into pan. Add sugar and butter and mix. Press cookie mixture over bottom and about 1 inch up sides of pan.
Bake crust in a 325° regular or convection oven until lightly browned, 10 to 12 minutes. Let cool about 5 minutes, then chill or freeze until cold, 5 to 10 minutes.
In a chilled large bowl, mix pumpkin, pumpkin pie spice, and 1/4 cup of the caramel topping until smooth. Add ice cream and mix until blended.
Working quickly, spoon about a third of the ice cream mixture into the cold crust. Drizzle with 2 tablespoons caramel topping and 2 tablespoons fudge sauce (if fudge sauce is too stiff, warm slightly in a microwave oven at full power (100%), stirring once, just until fluid, 15 to 30 seconds); sprinkle half the Candied Walnuts on top. Repeat with two more layers, omitting nuts on the top layer. Freeze until solid, about 5 hours, then cover and freeze up to 1 week.
About 15 minutes before serving, remove sides from pan, set torte on a serving plate, and let stand in refrigerator to soften slightly. Cut into wedges. Serve with additional caramel topping and fudge sauce (warm and stir again if too stiff) to add to taste.
For the smoothest texture, use a rich, full-fat ice cream. To soften slightly, heat it in the carton in a microwave oven at half power (50%) for 15 to 30 seconds.