Preheat the oven to 350 degrees F (175 degrees C).
Place the chicken breasts into a saucepan and fill with enough water to cover. Bring to a boil, then simmer over medium heat until chicken is tender enough to be pulled apart with a fork. Drain and cool until cool enough to touch. Shred or chop chicken and place in a 1 to 2 quart casserole.
Mix the cream cheese into the chicken until well blended, then stir in the ranch dressing and hot sauce. Top with Cheddar cheese.
Bake uncovered for 20 minutes in the preheated oven, until cheese is browned and the sauce is bubbly.