These Chicken Pot Pie “Soupy Toasts” Are Pure Winter Comfort Food

Name: These Chicken Pot Pie “Soupy Toasts” Are Pure Winter Comfort Food
Ingredients: 1 large loaf Italian bread , cut into 10 slices, 1/2 to 1-inch thick; 3/4 cup olive oil , divided; 1 medium yellow onion , finely diced; 2 small boneless, skinless chicken breasts , diced into 1/4-inch chunks ( 1 pound total); 1/2 teaspoon celery salt or kosher salt, plus more to taste; 1 teaspoon freshly ground black pepper , plus more to taste; 1 (12-ounce) bag frozen peas and carrots; 2 (0.87-ounce) chicken gravy packets; 1/4 cup water , plus more as needed; 10 deli slices cheddar cheese