Preheat the oven to 350°F (175°C).
In a mixing bowl, combine the shredded chicken, broccoli florets, cauliflower florets, and diced bell peppers.
In another bowl, blend the softened cream cheese and heavy cream until smooth. Add garlic powder, onion powder, Italian seasoning, salt, and pepper, mixing well.
Pour the cream cheese mixture over the chicken and vegetables. Stir until everything is evenly coated.
Spread the mixture evenly into the greased casserole dish. Top with shredded cheddar cheese.
Cover the casserole dish with aluminum foil and bake in the oven for 30 minutes.
After 30 minutes, remove the foil and bake for an additional 15 minutes, or until the cheese is bubbly and golden brown.
Once cooked, remove from the oven and let it cool for a few minutes. Garnish with sliced green onions before serving.