In a Dutch oven or large soup pot, heat the butter over medium-high heat until melted.

Add the onion, celery, and sliced carrots; sauté until they soften and become translucent, which takes about 5 to 7 minutes.

Toss in the sliced mushrooms and minced garlic, cooking until the mushrooms release their moisture and start to brown, around 4 to 5 minutes.

Sprinkle in the flour, stirring for about a minute to create a roux.

Gradually pour in the chicken stock while stirring to combine and avoid any lumps. Add the potato slices, salt, and black pepper, then bring to a boil.

Once boiling, reduce the heat and partially cover the pot. Cook until the potatoes are tender, about 12 to 15 minutes.

Stir in the shredded chicken, peas, corn, and cream. Let it simmer for an additional 4 to 5 minutes.

Taste and adjust the seasoning as necessary before garnishing with parsley and serving.