Melt 1 tbsp of oil in a saucepan over a medium heat and soften the onion for roughly 8 minutes. Add the grated garlic and ginger and cook for 2 mins until fragrant.
Add the cumin, turmeric, garam masala, chilli powder and cinnamon with a splash of water and stir to create a paste. Cook everything for 1-2 minutes until fragrant.
Add the sweet potato chunks, the coconut milk and veg stock. Bring to the boil, reduce the heat and simmer, uncovered, for 25-30 mins until the liquid has reduced right down and the starch has leached from the sweet potatoes to create a thick sauce. The potatoes should be soft.
Stir in the peanut butter until it mellows into the sauce- if your peanut butter is thick, try mixing it in a bowl with a splash of water to loosen it into a runnier paste so it is easier to stir into the pot. Then, add the spinach and chickpeas, mix well to combine and simmer for 2-3 minutes or until the spinach has wilted - you may need to add the spinach in batches. Add the juice of ½ lime and most of the coriander, saving a handful for garnish..Check for seasoning - adding more lime juice if desired. The curry should eventually reach a creamy consistency.
Serve into bowls, top with the remaining coriander, a dollop of yogurt, mango chutney and the roasted nuts, if desired for some crunch. Serve with cooked rice and naans, if you like.
