Heat olive oil in a large pot or Dutch oven over medium heat.
Add onion, carrots, and celery; sauté for 6 to 8 minutes until vegetables begin to soften.
Stir in minced garlic, cumin, and smoked paprika; cook for 1 minute until fragrant.
Add drained chickpeas and vegetable broth, then place the rosemary sprig on top.
Bring the soup to a boil, then reduce heat to low and simmer partially covered for 20 minutes.
Remove the rosemary sprig. Using a ladle, transfer 1 cup of the soup to a blender, puree until smooth, and return to the pot to thicken.
Stir in the baby spinach and lemon juice; cook for 2 minutes until spinach is wilted.
Season with salt and pepper to taste before serving.