Preheat the oven to 375°F. Line a baking sheet with aluminum foil and set aside.
Season the chicken breasts with salt, pepper and chili powder and place them in a pan with the water and ¼ cup of salsa
Raise the heat to medium-high and cover the pan. Turn the chicken a few times during cooking, and add more water if needed to keep the pan from drying out. The chicken should cook through in about 15-20 minutes, or when the internal temperature reaches 165ºF.
When the chicken is cooked, remove from the heat, let it rest for 5 minutes, and shred.
Place a layer of tortilla chips on the baking sheet. Layer with shredded cheese, chicken, and vegetables, then repeat with a second layer.
Bake until the cheese is melted.
Top the nachos with fresh chopped toppings and the remaining salsa.