In Dutch, we call this a zilveren Friese sierlepel
or silver Frisian ornamental spoon or silver commemorative spoon. The engraving could read: Jan van
(faded/rubbed) der Pol 1768 Klaaske Waters
is a Frisian girl’s name. Perhaps Jan van der Pol
married Klaaske Waters
in 1768. 18th Century Commemorative spoons were not often used as an eating utensil but used as a showpiece in a display cabinet, and many of those spoons have remain pretty good through time.
It’s not unusual to see Frisian spoons without town mark or assay marks, maker’s mark only or without any marks.
I believe the family name Waters to be of British origin which could explain the William & Mary theme. https://en.wikipedia.org/wiki/William_III_of_England