Heat olive oil in a large Dutch oven or heaven bottom pot over medium-high heat.
Add onions, garlic, and ginger. Cook, stirring frequently, until onions are translucent and just starting to turn golden brown - about 5 minutes.
Add cumnin, paprika, coriander, tumeric, chili powder, and black pepper, stirring frequently until aromatic - about 30 seconds.
Add crushed tomatoes and spinach. Cook, stirring occasionally, until spinach is wilted - about 2 minutes.
Add half of cilantro and chicken stock. Stir to combine. Cover pot and simmer for 30 minutes.
Remove lid and stir in drained chickpeas, lemon juice, and chicken. Simmer, stirring frequently, until sauce is thickened - 5-10 minutes. Season to taste with salt.
Remove from heat and stir in the half & half and garam masala. Serve immediately, garnished with remaining cilantro leaves. Serve with basmati rice or naan bread.