Preheat the oven to 350°F (175°C).

Boil the chicken in a large pot until fully cooked.

Debone and chop up the chicken into bite-sized pieces.

In a mixing bowl, combine the milk, Velveeta cheese, cream of mushroom soup, and Rotel tomatoes.

Bring the mixture to a boil, stirring often.

Add the chopped chicken to the mixture and simmer for 5-10 minutes, stirring frequently.

In a long casserole dish, place a layer of Doritos at the bottom.

Pour half of the chicken and cheese mixture over the Doritos.

Add another layer of Doritos, followed by the remaining chicken mixture.

Top with a final layer of Doritos.

Bake in the preheated oven for 30 minutes or until the top is golden brown and bubbly.

Serve hot.