Marinate chicken with olive oil and poultry seasoning for 10 minutes.
Cook chicken until golden, then set aside. Slice bread and spread garlic butter mixture on both halves.
Toast bread until golden, then prepare Alfredo sauce in same pan with butter, garlic, parsley, and red pepper flakes.
Add cream, parmesan, and remaining parsley; simmer until slightly thickened. Spread sauce on bread, top with chicken and mozzarella, then bake for 5 minutes.
Notes
For extra flavor, sprinkle additional parsley or cheese before serving.