Preheat the oven to 400°F (200°C) and lightly spray a casserole dish with cooking spray.
Place the chopped cauliflower in a large microwave-safe bowl with a splash of water, cover, and microwave until fork-tender, about 15 minutes; drain well.
Meanwhile, bring a small pot of salted water to a boil. Add the chicken chunks and cook 10–12 minutes until no longer pink; remove and let cool slightly.
Drain the cauliflower and transfer to a food processor. Add light coconut milk, peanut butter powder, natural peanut butter (1/4 cup + 2 tbsp), fish sauce, sriracha (1 tbsp + 1 tsp), coconut sugar, lime juice, minced garlic, minced ginger, and salt. Process until smooth and creamy, scraping down the sides as needed.
Shred the cooked chicken with two forks and fold it into the cauliflower–peanut sauce in a large bowl.
Add the halved snow peas, chopped red bell pepper, finely chopped red cabbage, thinly sliced carrot, and minced cilantro to the chicken mixture and stir until everything is evenly coated.
Spoon the mixture into the prepared casserole dish, spread evenly, cover, and bake for 30 minutes. Uncover and bake an additional 10 minutes until edges brown and top is golden.
Let the casserole rest a few minutes before serving and garnish with extra cilantro, diced green onion, toasted peanuts, and more sriracha if desired.
