Pull the skin off the chicken thighs, using your hands and a serrated knife if needed. Season both sides with salt and pepper.
Warm a large skillet over medium-high heat and add the oil.
Once the pan is hot, place in 3 chicken thighs, leaving space between them so they brown instead of steam. Cook for about 2 minutes until golden underneath, then turn and cook the second side for another 1 to 2 minutes. Transfer to a plate.
Brown the remaining 3 thighs the same way. Add a little more oil only if the pan looks dry.
In the slow cooker, pour in the coconut milk. Add the dried basil, salt, pepper, curry powder, and chili powder, then stir until blended.
Mix in the chopped onion, garlic, and jalapenos.
Nestle the browned chicken into the sauce and spoon some of the mixture over the top.
Cover and cook on high for 4 to 5 hours or on low for 6 to 8 hours.
When the chicken is fully tender, lift it out and place it on a plate or cutting board. Let it rest for a few minutes.
Stir the ginger into the slow cooker.
In a small bowl, whisk together the cornstarch and cold water until smooth. Pour the mixture into the slow cooker and stir well.
Pull the chicken meat from the bones and shred it, discarding the bones and any tough pieces.
Return the shredded chicken to the sauce, stir everything together, and cover again for about 10 minutes so the sauce thickens slightly.
Taste and adjust with more salt and pepper if needed. Finish by stirring in the fresh cilantro.
Serve warm with rice, cauliflower rice, or naan.