A slick trick--a super dessert! Be ready to serve seconds--you'll have requests. Cut jelly roll into 1/2-inch slices. Arrange slices over bottom and around sides of oiled 2 1/2-quart mixing bowl. Dissolve gelatine in hot water. Add marshmallows and partially drfrosted strawberries, stirring until marshmallows dissolve. Add lemon juice and chill until partially congealed. Beat until fluffy. Beat egg whites until soft peaks form. Gradually beat in sugar. Fold into gelatin mixture. Blend in whipped cream and nuts. Pile mixture lightly into jelly roll-lined mold. Chill until firm. Unmold and serve. Makes 1 O to 12 servings.