Preheat oven to 350F.
Lightly grease a 9x13 casserole and set aside.
Place broccoli in a pot of boiling water and cook for 3 minutes until tender but still crisp.
Using a slotted spoon remove broccoli and let it drain completely.
In a large pot or dutch oven melt butter on medium heat and sauté onion and celery for 3 minutes.
Add milk, chicken broth and stir in bouillon. Cook for 3 minutes reduce heat to medium low.
Add in cream cheese pieces whisking slowly until it completely dissolves and you get a smooth creamy sauce.
Remove from heat and add mayonnaise, sour cream and continue to whisk until they are all creamy and nice.
Mix in curry powder if using, 1 cup of cheddar cheese, chicken and cooked broccoli.
Pour mixture into your prepared casserole and bake in the middle of your oven for 10-15 minutes or until bubbly.
Top with remaining cheese and return to oven for another 5 minutes or until cheese melts.