creamy chicken broccoli casserole

Ingredients

• 1/2 stick butter
• 1/2 cup diced onion
• 2 cups chicken stock
• 3/4 cup sour cream
• 2 tablespoons mayonnaise
• 1/2 teaspoon poultry seasoning
• 1/2 teaspoon salt
• 1 teaspoon pepper
• 4 cups steamed broccoli (i buy the broccoli in the bag for steaming)
• 4 cups diced roasted chicken (bought works great)
• 2-3 cups cheese of choice (grated)
• 1 can french fried onions
• 2 packages uncle ben's basmati rice,(do in microwave)