Preheat the oven to 375°F.
Cut each croissant in half length-wise and width-wise.
Arrange the bottom half of each croissant piece in a rimmed baking dish. Slather (generously - trust!) the maple mustard dressing onto each piece of croissant.
Then layer each piece with ham and lots of shredded Gruyère.
Sprinkle lots of the fresh chives on each piece, then cover with the top piece of the croissant.
Cover the entire baking dish with aluminum foil and bake for 15 minutes covered.
Remove foil and then bake for an additional 2-4 minutes until cheese is bubbling and tops of croissants are lightly golden.
Serve with an additional garnish of chives, and a side of the maple mustard dressing, and dip in the dressing while eating, if desired.Enjoy! (These sandwiches can be kept in the fridge in an airtight container for 2-3 days. They make great leftovers.)