Heat oil in a large pot over medium heat. Add the diced onion and cook for about 5 minutes, stirring occasionally, until softened and translucent.

Stir in the garlic, ginger, curry paste, and cinnamon. Sauté for 1 minute until fragrant.

Add the pumpkin, coconut milk, and brown sugar. Bring to a boil, then lower heat, cover, and simmer for 5 minutes.

Remove the lid and continue simmering about 10 minutes, stirring occasionally, until the sauce thickens and the pumpkin becomes tender.

Remove from heat and stir in the basil, lime juice, and salt. Serve over rice topped with roasted cashews.