Heat 1 tablespoon oil in a large nonstick skillet over medium-high heat. Add the onion, garlic, and ginger and saute until softened, about 4 to 5 minutes.
Over medium heat, add the salt, coriander, garam masala, turmeric, cumin, cardamom, and chili powder, and stir on medium-low heat until fragrant, about 30 seconds.
Dissolve the tomato paste in the water and stir into the spices in the pan, creating a thick spiced sauce, about 1 minute.
Add the spinach and gently stir to combine. Cover and raise the heat to medium-high, allowing the spinach to start to wilt, about 3 to 5 minutes.
Transfer spinach mixture to a blender or food processor and puree until relatively smooth but still a bit chunky.
Wipe the skillet clean, return it to medium-high heat, and add 1 tablespoon of oil. Add the cubed chicken pieces, sprinkle salt over the top, and cook until almost completely cooked through, about 5 to 7 minutes.
Pour the spinach mixture back over the chicken and cook for another 2 to 3 minutes. Stir in the yogurt, and serve immediately with basmati rice and/or naan.
