I make mine a little different. I "marinate" my strawberries in the the liqueur. Instead of whipped cream, I use Bavarian Cream. This is how it was served to me at "The Shadows" a wonderful restaurant in an Old Plantation home across Lake Pontchartrain from New Orleans. Yes, It was a victim of Katrina.
For 10-12 servings, 3 quarts strawberries, 1 pt. whipping cream, about 1/2 cup sifted confectioners sugar (icing sugar) and flavoring. We used orange extract instead of Grand Marnier.