In a medium bowl, stir together the yogurt, lemon juice, ginger, garlic and garam masala. Transfer the yogurt mixture to a large resealable plastic bag and add the chicken, being sure to coat each piece. Refrigerate for at least 1 hour or overnight.
Preheat the oven to 425 degrees . Place the chicken on a foil-lined rimmed baking sheet, season with salt and roast until juices run clear, about 45 minutes. Let the chicken stand for 5 minutes before serving.
Meanwhile, in a medium saucepan, bring 1-1/2 cups salted water to a boil. Remove from the heat and stir in the couscous and dates. Cover and let stand for 5 minutes. Uncover and fluff with a fork. Stir in the toasted almonds and parsley. Serve with the chicken.