Heat a wide sauté pan with the olive oil. Add the chicken thighs and sear until golden, 5 to 7 minutes. Transfer to a tray.
Add the garlic and Swiss chard to the pan and cook until the greens reduce, about 3 to 4 minutes.
Stir in the spices, chickpeas, and half of the preserved lemon. Mix well, then add the rice and stir to coat. Return the chicken to the pan and pour in 3 cups/720 milliliters hot water. Cover and cook over low heat for 25 minutes.
Cover the pan with parchment paper and then foil. Transfer to a preheated 355°F/180°C convection oven and bake for 30 minutes.
Remove the cover during the last 10 minutes to brown the top. Serve warm straight from the pan.