Heat the oil in a skillet over medium heat. Cook the onion for 4-5 minutes until softened, then add the garlic, ginger, and red curry paste. Cook 1-2 minutes, stirring constantly, until the paste darkens and smells fragrant.
Scrape the mixture into the slow cooker.
Add the butternut squash, chickpeas, bell pepper, vegetable broth, soy sauce, brown sugar, turmeric, and about three quarters of the can of coconut milk. Reserve the rest. Stir to combine.
Cover and cook on LOW for 4 hours, or HIGH for 2 to 2 1/2 hours, until the squash is tender at the center but still holding its shape. Check early - squash goes from tender to mush quickly.
Stir in the reserved coconut milk and the spinach. Cover and cook 10 more minutes, just until the greens wilt.
Turn off the heat. Stir in the lime juice and half the herbs. Taste and adjust with more soy sauce, sugar, or lime.
Serve over jasmine rice, topped with the remaining herbs, chopped peanuts, and a lime wedge.