To make kabocha puree: Preheat oven to 375. Halve a kabocha squash and place both sides cut side down in a baking dish. Fill the baking dish with water. Bake for 40 minutes or until the flesh can be easily pierced with a knife. The baking time may need to be adjusted depending on the size of your kabocha. Remove the kabocha from the oven and let cool. Remove and dispose of seeds using a spoon. Scoop out the flesh using a spoon. Use an immersion blender or food processor to puree the flesh, adding water until you have a smooth puree.
To roast butternut squash: Preheat oven to 450. Remove skin and cut the butternut squash into bite-sized pieces. Toss with olive oil, salt and pepper. Roast for 15 minutes or until the squash is soft and has just started to caramelize.
Heat 2 tablespoons of olive oil at a high heat in a heavy bottomed pan. Add chicken and cook until sealed. Take chicken out of the pan and set aside.
Reduce heat to medium, add onions and ginger and stir until onion has become translucent. Add garlic and stir for 30 seconds more.
Add chopped tomatoes and kabocha puree to the pan, bring to boil and reduce to a simmer for 10 minutes.
Add stock, coconut milk, curry and chili powder. Bring to a boil and reduce to a simmer for 10 minutes, stirring occasionally.
Add chicken and roasted butternut squash and simmer for 10 minutes.
Add cilantro and additional salt and pepper to taste.
Serve with naan and/or rice.