Preheat an oven to 400 degrees F. Line a baking sheet with parchment paper and set aside.

Cut the kabocha squash in half and scoop out the seeds using a spoon. Cut the squash into wedges and place them on the prepared baking sheet. Drizzle with 1 tablespoon of olive oil and sprinkle with salt and pepper. Roast for 20 minutes, until just tender. Cool for 15 minutes and then peel the skin off or use a small paring knife to remove the skin.

Heat a dutch oven or braiser over medium heat and add the remaining olive oil. Add the curry paste and kaffir lime leaves and cook for 3-4 minutes, stirring often, until the curry paste is very fragrant. Add the Thai chilies and coconut milk and stir until very smooth. Bring to a simmer and the fish sauce and palm sugar. Stir until the sugar is dissolved. Season to taste with salt and pepper.

Add the cornstarch mixture to the curry and stir well. Simmer for another 5 minutes or so, until very thick. Add the onion and bell peppers and Thai basil leaves, stir and cover for 5 minutes. Once the vegetables are tender, add the roasted kabocha squash and cook for another 5 minutes.

Serve over jasmine rice with more Thai basil leaves and chili oil.