Cut pound cake into 2 horizontal layers. Set aside. In a med. Bowl, mash thawed blackberries. Add walnuts & raspberry jam to mashed blackberries. Spread layers of pound cake w/ blackberry & raspberry jam mix. Set aside. In mixing bowl, add bananas into whipped topping. Mix well. Immediately top each berry mix layer w/ the banana mix. Stack layers. In a small bowl, combine sour cream, confectioners sugar & vanilla extract. Spread sour cream mixture on top. Cut & serve. Approximately 7 minutes. Per serving (excluding unknown items): 2389 Calories; 63g Fat (27% calories from fat); 27g Protein; 353g Carbohydrate; 314mg Cholesterol; 2272 mg Sodium By Patty on Nov 9, 1998. Recipe by: FOOD IN A FLASH SHOW #FF2097