In a large pot, combine 1 cup of chicken broth and the chicken breasts. Bring to a boil, then reduce the heat and simmer until the chicken is cooked through, about 15-20 minutes. Once cooked, remove the chicken and shred it using two forks.
In the same pot, add the remaining 1/2 cup of chicken broth, the drained diced tomatoes, taco seasoning, and optional cayenne pepper. Stir to combine, bringing the mixture to a gentle simmer.
Cut the cream cheese into pieces and add it to the simmering mixture. Stir continuously until the cream cheese is fully melted and incorporated.
Add the shredded chicken and white beans to the pot. Stir until everything is well mixed. If the mixture seems too thick, you can add a bit more chicken broth to reach your desired consistency.
In a small bowl, mix the cornstarch with a tablespoon of water to create a slurry. Add this to the dip and stir continuously until the dip thickens, about 2-3 minutes. Season with salt and black pepper to taste.
Stir in the shredded Mexican blend cheese until it melts and the dip is creamy and luscious.
Transfer the dip to a serving dish and garnish with finely diced Roma tomatoes, chopped cilantro, and sliced jalapeños. Serve warm with tortilla chips for dipping.
