Heat the oil in a large saucepan and add the onion. Cook for 2-3 minutes until beginning to soften and then add the peppers. Cook for another 3-4 minutes until the peppers are just becoming tender.
Add the chilli powder, cumin and paprika to the pan and stir through, cooking for a minute. Put the mince in the pan and move around, breaking up with a wooden spoon. Cook for 3-4 minutes until brown all over.
Pour in the passata and stock. Bring to a gentle simmer and cook for 30 minutes.
Put the chocolate in a heatproof bowl and heat in the microwave for around 30 seconds until melted. Add this to the chilli, along with the beans. Alternatively, you can add the pieces of chocolate straight to the chilli. Stir to combine, then simmer for another 15 minutes until the mixture has thickened slightly.
Meanwhile, prepare the rice according to packet instructions and serve with the chilli.
Tip: adding any more than 2 squares of chocolate will take over the flavour of the chilli, so in this recipe, less is more!