Heat a large skillet over medium-high heat and add the butter or oil.
Add the chicken, curry powder, and sliced onion to the skillet; cook about 3 minutes, stirring occasionally, until the outside of the chicken is lightly browned.
Add the chopped garlic and jalapeños and cook 2 more minutes until fragrant.
Pour in the coconut milk, tamari (or soy/fish sauce), and honey, stirring to combine.
Stir in the shredded kale or spinach and season with salt and black pepper; simmer 5–10 minutes until the chicken is cooked through and the greens are wilted.
Remove from heat and stir in the fresh basil, lime juice, and roasted cashews (if using).
Serve the curry over steamed rice and garnish with extra basil or lime if desired.