Pre-heat your oven to 180 fan
Combine the popcorn, melted butter and salted caramel sauce into a food processor. Blitz up until the pieces have broken down into smaller chunks.
Press the popcorn mix into a tart tin / dish. Make sure it's pressed in firmly - You can use the bottom of a glass if easier, this will help keep the surface even and flat too.
Refrigerate for an hour. This will allow everything to set firmly.
Whilst the popcorn base sets in the fridge, make the filling.
In a separate bowl, combine the sugar, salt, nutmeg and cinnamon. Mix in the beaten eggs, melted butter and milk, then add in the pumpkin puree and stir thoroughly to combine. Pour the mix into the popcorn base and cook for 15-20 minutes. Keep an eye on the filling whilst it cooks. You want to ensure it is firm with a slight wobble, that's when you know it's cooked all the way through.
Remove from the oven and allow to cool fully before slicing up and serving with a dollop of cream.