Preheat the oven to 430F / 220C (200C fan). Line a large roasting tin with non-stick baking paper.
Arrange the squash in the roasting tin and sprinkle the spices (turmeric, chilli powder, cinnamon and curry powder) and 1 TBSP oil on top. Give it a good stir to ensure the squash is thoroughly coated in the spices then roast for 20 minutes.
Meanwhile, gently heat ½ TBSP oil in a large saucepan. Add the mustard seeds and cook until they start to pop. Stir in the onion and cook for a couple of minutes until it starts to soften (add a splash of water if it starts to stick). Add the garlic and ginger (and fresh chilli, if using) to the pan, and continue cooking for one minute. Finally add the tofu chunks (or other protein source), the coconut milk and vegetable stock. Bring to the boil then reduce the heat to low, partially cover with a lid and gently simmer for about 10-15 minutes.
Once the squash has roasted for 20 minutes, add the bell pepper to the roasting tin and stir through. Continue cooking until for another 10 minutes or so, until both the squash and pepper are tender.
Tip the roasted vegetables into the saucepan and stir through to coat in the coconut milk. Simmer for a couple of minutes to allow the flavours to meld. Finally, add the spinach and stir through until it wilts.
Taste test and season with salt, if desired.
Any leftovers can be stored in the fridge for up to three days (be sure to check the storage instructions for the tofu or other protein source that you are using).