In a large 5 quart pot stir together butter, diced onion, minced garlic, diced celery and sliced mushrooms over low heat until butter is melted and vegetables have started to soften. This will take about 3 minutes.
Stir in flour until white is no longer visible, about 1 to 2 minutes.
Stir in chicken stock, milk, heavy cream, carrots, potatoes, peas, corn, chicken, Italian seasoning, garlic powder, thyme, salt, pepper and bay leaves.
Stir all together until well mixed then bring to a boil and then turn down the heat to a simmer
Simmer over low heat, about 2 on stove dial, until potatoes are tender. This will be about 10 to 15 minutes. Stir often so this doesn’t come to a boil or burn at the bottom.
Remove from heat. Remove both bay leaves.
Serve hot and sprinkle fresh parsley over the top of each serving.