However, you could use these options depending on the context:
* A box of chocolates (common and straightforward)
* An assortment of chocolates (emphasizes variety)
* A selection of chocolates (similar to "assortment")
* A collection of chocolates (implies a more deliberate gathering)
* A treasure trove of chocolates (for a playful and indulgent feeling)
* A mountain of chocolates (for a humorous and exaggerated amount)
Ultimately, the best collective noun for chocolates depends on what you want to emphasize and the overall tone of your writing.