Spinach Dip Unverified!

• 1 pkg frozen chopped spinach, thawed and drained
• 1 pkg Knorr's leek soup mix*
• 1 cup mayonnaise
• 1 cup sour cream
• 1 can water chestnuts, chopped

[The variation of this recipe in my mother's collection uses vegetable soup mix and allows the preparation note that says that it should be allowed to chill several hours to let the flavors develop]