Preheat oven to 350°F (175°C)

In a large skillet, melt butter over medium heat

Add sliced mushrooms and sauté until tender and lightly browned

Stir in minced garlic and cook until fragrant

Add chicken pieces to the skillet and brown each side lightly

Sprinkle salt, pepper, and Italian seasoning over the chicken

Stir cream cheese and heavy cream into the skillet until smooth

Allow mixture to become creamy and well-blended

Transfer chicken and mushroom mixture to a greased casserole dish

Spread evenly and pour remaining sauce over top

Sprinkle shredded mozzarella cheese across the casserole

Bake for 25–30 minutes until bubbly and cheese is lightly golden

Remove from oven and let rest briefly before serving