Preheat oven to 325 degrees F. Melt 4 tablespoons of the butter, add sherry, and boil 1 minute. Add lobster and remove from heat. In a medium saucepan, melt remaining butter. Add flour and cook, stirring, until mixture bubbles. Remove from heat. Drain and reserve the sherry from the lobster meat, then slowly stir sherry and cream into the mixture until thoroughly blended. Return to heat and cook, stirring constantly, until sauce is smooth and thick. Spoon 4 tablespoons of the sauce into a small bowl. Add beaten egg yolks, 1 tablespoon at a time, stirring well after each addition. Return egg mixture to sauce and mix well. Stir over low heat about 3 minutes; do not allow to boil. Remove from heat and add lobster. Turn into four individual ramekins or a small, deep pie plate. Combine topping ingredients, blend well, and sprinkle over pie(s). Bake about 10 minutes to heat through.