Mexican Chicken Casserole with Tortilla Chips

INGREDIENTS

2 cups

leftover chicken ((about 2 chicken breasts fully cooked and chopped))

1/2 lb

tortilla chips

2 cups

cheddar cheese (grated)

15 oz

canned tomatillos (drained and diced)

1/2

red pepper (diced (optional))

1/4 cup

button mushrooms (diced (optional))

3 oz

chipotles in adobo sauce ((about half a 6.5 ounce can))

10 oz

canned cheddar cheese soup

medium onion (peeled and halved)

garlic cloves

1 tbsp

milk

salt and pepper