Start by placing the chicken breasts in a large pot and pouring in 1 cup of chicken broth. Bring to a boil, then reduce the heat and let simmer for about 15-20 minutes, or until the chicken is cooked through. Remove the chicken from the pot and shred it using two forks. Set aside.
In the same pot, add the remaining 1/2 cup of chicken broth, diced tomatoes, taco seasoning, and optional cayenne pepper. Stir to combine all the flavors.
Add the cream cheese to the pot and stir until melted and well combined. The mixture should be creamy and smooth.
Stir in the shredded Mexican blend cheese, cornstarch, and white beans. Mix until everything is combined and the cheese is melted.
Fold in the shredded chicken and season with salt and black pepper to taste. Allow the dip to simmer for an additional 5 minutes, stirring occasionally.
You can serve the dip directly from the pot or transfer it to an oven-safe baking dish. If baking, preheat your oven to 350°F (175°C) and bake for about 15-20 minutes, or until bubbly and golden on top.
