Step 1

Add the tomato passata, salt and chickpeas to the slow cooker and mix through.

Step 2

Scatter the garlic and ginger over the top.

Step 3

Place the slices of butter over the top, then add the ground spices on top of the butter.

Step 4

Cover and cook on LOW for about 1 hour, until the butter is melted and the spices are fragrant.

Step 5

Open the lid and stir the curry well, getting the spices and butter mixed into the sauce and scraping the sides and the bottom to be sure that the tomato sauce isn't sticking.

Step 6

Cover and cook for another 2-3 hours. The first time you make this, it is worth opening the lid and giving it a stir at the halfway point if you can, just to be sure it isn't sticking. If you see no signs that it's sticking, then you'll know for next time that you can leave it cooking without stirring - but all slow cookers are a little different so you want to get to know how your particular model behaves.

Step 7

Once you're ready to eat, stir the cream through the pan and cover for another 15 minutes until warmed through - you use this time to prepare your rice and/or naan bread.

Step 8

Serve with a sprinkle of fresh cilantro (coriander) and lemon wedges for squeezing.