I would like to make this ahead of time for a party. Is this one of those recipes that improves as it rests? How long would you say this keeps,...

This does look a dish with favors that would intensify for the second day. I'd say it is fine in the fridge for 2 days, but if you want to make it ahead more than that, consider freezing it and gently reheating on the day of the party in your slow cooker or oven.