Heat 2 tablespoons oil in a large skillet over medium-low heat. Cook onion and rosemary, stirring, until fragrant, about 1 minute. Stir in garlic powder, paprika, and tomato paste and cook, stirring, 15 seconds. Add chickpeas, tomatoes, spinach, salt, pepper, and water and bring to a boil. Reduce to a simmer and cook, covered, over low heat, stirring occasionally, until flavors have combined and mixture is piping hot, 5 to 7 minutes.
Meanwhile, heat remaining 2 tablespoons oil in a small skillet over medium heat. Cook panko, stirring, until toasted and lightly browned, about 3 minutes.
Divide stew among serving bowls and top each with 2 tablespoons panko.