Split each hen down its back and open it up flat.

Arrange the hens, skin side up, on two large roasting pans.

Squeeze the lemons and oranges over the hens, then place the squeezed lemon and orange pieces underneath the hens.

Sprinkle the garlic with the salt on a work surface.

Chop and smear them together with a large knife to form a paste.

Scrape the garlic paste into a small bowl.

Stir in the paprika, cumin, ginger, and cayenne pepper (if using).

Gradually stir in the olive oil to make a paste.

Spread the paste on the hens' skin.

Let them stand at room temperature, covered, for 1 hour.

Position a rack in the top third of the oven and preheat to 400°F.

Roast the hens, basting often with the drippings, until the juices run clear when the flesh is pierced with a fork, about 50 to 60 minutes.

Serve immediately, discarding the cooked fruits.