Easy Chicken Tetrazzini Casserole

INGREDIENTS: For the Chicken Tetrazzini: 12 oz thin spaghetti or linguine 4 cups shredded rotisserie chicken *or cook 2 lbs chicken breast 1 lb button mushrooms thickly sliced 1 medium onion finely chopped 3-4 garlic cloves minced 2 Olive Oil For the Creamy Sauce: 4 Tbsp unsalted butter 1/3 cup all-purpose flour 2 1/2 cups low sodium chicken broth 1 Tbsp lemon juice 1 1/2 cups half and half or sub with equal parts milk & heavy cream 1 tsp sea salt or to taste 1/4 tsp black pepper, freshly ground 1/4 cup parsley, chopped, plus more to garnish 1 1/2 cups shredded mozzarella cheese.