While the veggies are roasting in the oven, set 6 cups of water to boil in a large pot or ducth oven over high heat.
Once the water boils, add salt and chicken breasts. Depending on the thickness of the breasts it'll take 5-15 minutes.
Make sure the chicken cooks all the way through, and use a meat thermometer to easily check. You want the internal temperature of the chicken to be at least 165°F.
Once the chicken is cooked all the way through, let rest for a few minutes.
Once the chicken has rested, put it in a stand mixer and mix on low or stir with the paddle attachment. Mix until the chicken is shredded, it'll take a few minutes.
Take 1 cup of enchilada sauce and mix it with your shredded chicken. Set aside
Spread ½ cup of the green sauce on a 9 by 13 baking pan.
Warm up your tortillas.
Start forming the enchiladas by placing some of the shredded chicken in the middle of the tortillas. Roll each tortilla and place in the baking pan.
Repeat with all your tortillas, or until the baking pan is full.
Drizzle the remaining green sauce on top of the rolled enchiladas.
Top with shredded cheese, ensuring that you cover the whole pan.
Stick the pan in the oven under the broiler. Eyeball it, and only take it out of the oven when the cheese is all melted and bubbly.