Peel and finely chop the onion and garlic, then peel and dice the sweet potato. Cook the sweet potato in boiling water until tender, then drain and mash.
Meanwhile, heat the oil in a medium pan on a low heat, add the onion and fry for 8 minutes, or until softened. Add the garlic, turmeric and garam masala and cook for 2 to 3 minutes. Drain the chickpeas and add them to the pan along with the spinach. Place the lid on and cook for 5 to 10 minutes, or until the spinach has wilted or defrosted. Mash the mixture with a potato masher to make a fairly smooth mixture with some soft lumps, then leave to cool. Serve the cooled chickpea smash with the mashed sweet potato. For more information on stages of complementary feeding, click here.