Wikipedia
Normande sauce, also referred to as Normandy sauce and sauce Normande, is a culinary sauce prepared with velouté, fish velouté or fish stock, cream, butter and egg yolk as primary ingredients. Some versions may be prepared using both fish velouté and fish stock. Some may be prepared simply using a velouté base and the addition of cream, which are cooked together. Cider or dry white wine may also be used as primary ingredients.
Some versions may use mushrooms or mushroom ketchup in its preparation Additional ingredients may include fish liquor ( fish sauce), oyster liquor, mushroom liquor and lemon juice. Seasonings may include cayenne pepper, black pepper and salt. Some versions may be strained prior to use. The sauce may be used with seafood dishes, fettuccine dishes and on vegetables.