Make a simple syrup by combining the raw sugar and water in a saucepan and cooking over low heat until the sugar is dissolved. Remove from the heat and let cool.
Next, drain the water from the canned chestnuts. Place in a food processor and puree. Add the simple syrup and Grand Marnier, to taste, while blending (chef's tip: make it a bit sweeter then you like). Lay the torn chunks of pound cake in the bottom of 4 serving glasses. Add 2 tablespoons of Marsala to each and then some chestnut puree on top of the poundcake. Refrigerate for 1 hour.
After removing it from the refrigerator, add layers of the whipped cream and caramel sauce. Top with blackberries and walnuts before serving.
Professional Recipe: This recipe was provided by a chef, restaurant or culinary professional and makes a large quantity. The Food Network Kitchens chefs have not tested this recipe in the proportions indicated and therefore cannot make any representation as to the results.