Peel and core pears; cut into ¼-inch slices. Marinate in lemon juice to keep from browning.
Combine Roquefort, cream and cognac, and mash to a smooth paste. Add lemon juice (from pears) and paprika, to taste.
Sandwich cheese mixture between pear slices; place on a bed of Cos lettuce leaves and dress with French Dressing; sprinkle with halved walnuts.