Start by greasing your Instant Pot's inner pot.
Create a base layer of crushed Doritos in the Instant Pot.
Spread the shredded chicken evenly over the Doritos layer.
Sprinkle half of the shredded cheddar cheese over the chicken.
In a bowl, mix the cream of chicken soup, milk, and sour cream until smooth. Pour this creamy mixture over the cheese layer.
Repeat the layering process: Doritos, chicken, the remaining cheddar cheese.