To make crust: In medium bowl, combine crushed chocolate wafers, margarine and sugar; mix well.
Set aside 1/4 C of the mixture and press remaining mixture onto bottom of 9x13-inch pan. Refrigerate for 15 minutes.
Carefully spread chocolate fudge sauce over crust, using tip of a rounded knife and being careful not to pull up crust.
Cut slightly softened ice cream into slices and place them over the fudge, cutting pieces to fit.
Place spoonfuls of sherbet randomly over ice cream and gently swirl into the ice cream.
If the ice cream mixture starts to get too soft, set pan in freezer until it firms up slightly.
Top with raspberries, gently pressing them into the ice cream mixture, then cover with whipped topping, bringing it to the edges of the pan.
Garnish with reserved chocolate crumbs, cover, and freeze 6 hours or overnight.
Let stand at room temperature about 10 minutes before serving.
Note: For easy prep, buy a half gallon of ice cream and cut it in half. Freeze one half to use in other desserts. Let the other half soften just enough to cut it into slices. If desired, 1 quart of ice cream can be used. Soften, then evenly spread over fudge.