The tart is ready when it is nice and golden brown.
Serve to your guests, warm if possible, with a green salad.
Remarks
If you don't have Maroilles cheese, you can use other ones instead. I advise you to go for a rather soft strong cheese like Reblochon, Munster, Morbier, etc.
You can also replace puff pastry by shortcrust.
And to drink?
A good beer, possibly from the northen France, a jenlain for example.