Preheat oven to 400 degrees.
Heat a medium saucepan to medium heat. Add butter and onions and cook until onions are tender.
Add cream cheese, milk, sour cream, dill, parsley and black pepper. Stir until cheese is melted and creamy.
Add shredded chicken, buffalo sauce and cheddar cheese and stir to combine. Remove from heat.
Pour dip into an oven safe dish and bake in the oven for about 10 minutes until top is golden and bubbly. Remove dip from the oven and sprinkle with chopped green onions (optional).
Dip with crostini, sliced baguette, celery sticks or carrots.