Heat 2 tablespoons oil in a large saucepan over high heat. Add chopped onion, chopped garlic, 2 tablespoons taco seasoning and ⅛ teaspoon salt. Cook, stirring often, until fragrant and the onion starts to soften, 3 to 5 minutes.
Stir in 4 cups broth, the rinsed chickpeas, chopped sweet potatoes and diced tomatoes. Cover and bring to a boil over high heat. Reduce heat to maintain a lively simmer; cook, covered and stirring occasionally, until the sweet potatoes are tender, 8 to 10 minutes.
Stir in the softened cream cheese; return to a lively simmer. Stir in 5 ounces baby spinach; cook until wilted.
Divide the soup among 6 bowls. Garnish with cilantro and tortilla strips, if desired.
