Preheat your oven to 375°F (190°C). This ensures that your casserole cooks evenly and thoroughly.
In a large pot, steam the chopped cauliflower until it is just tender, about 5-7 minutes. You want it to be cooked but still firm enough to hold its shape in the casserole.
While the cauliflower is steaming, heat a skillet over medium heat. Add a splash of oil, then add the chicken breast. Season with salt and cook until it is no longer pink in the center, about 6-8 minutes. Remove from the skillet, let it cool slightly, and then chop it into bite-sized pieces.
In a mixing bowl, combine light coconut milk, peanut butter powder, natural peanut butter, fish sauce, sriracha, coconut sugar, lime juice, garlic, ginger, and salt. Whisk until smooth and creamy. Adjust the spiciness by adding more sriracha if desired.
In a large casserole dish, combine the steamed cauliflower, chopped chicken, snow peas, red bell pepper, red cabbage, carrot, and minced cilantro. Pour the peanut sauce over the top and gently mix everything together until well combined.
Cover the casserole dish with foil and bake in the preheated oven for 25 minutes. Remove the foil and bake for an additional 15-20 minutes, or until the top is golden and bubbly.
Once out of the oven, let the casserole cool for a few minutes. Garnish with additional cilantro, diced green onion, and toasted peanuts before serving.
