Preheat the Oven: Preheat your oven to 350°F (175°C).
Prepare the Sauce: In a large skillet, melt the butter over medium heat.
Add minced onion and garlic to the skillet. Sauté until the onion becomes translucent and fragrant, about 3-4 minutes.
Sprinkle flour over the onion and garlic mixture. Stir continuously and cook for about 1-2 minutes to make a roux.
Slowly pour in the chicken broth while stirring constantly to avoid lumps. Continue cooking until the mixture thickens, usually about 3-4 minutes.
Reduce the heat to low and stir in sour cream, green chilies, cumin, salt, and black pepper. Cook for an additional 2-3 minutes until everything is well combined and heated through. Remove from heat.
Prepare the Chicken Mixture: In a separate bowl, combine the shredded chicken breast, one cup Monterey Jack cheese, and add one cup of the white enchilada sauce. Mix until evenly distributed.
Assemble the Enchiladas: Take a flour tortilla and spoon a portion of the chicken and cheese mixture onto the center of the tortilla. Roll it up tightly and place it seam side down in a lightly greased 9x13 inch baking dish.
Repeat the process with the remaining tortillas and chicken mixture, arranging the rolled enchiladas snugly in the baking dish.
Pour Sauce and Add Cheese: Once all the enchiladas are assembled in the baking dish, pour the prepared white sour cream sauce evenly over the top of the enchiladas.
Sprinkle the remaining shredded Monterey Jack cheese on top of the sauce.
Bake: Place the baking dish in the preheated oven and bake for 25-30 minutes, or until the cheese is melted and bubbly, and the enchiladas are heated through.
Garnish and Serve: Once baked, remove the enchiladas from the oven and let them cool for a few minutes.
Garnish the enchiladas with sliced green onions, chopped cilantro, and chopped avocado.
Serve hot and enjoy your delicious White Sour Cream Sauce Chicken Enchiladas!
These enchiladas pair well with a side of rice, beans, or a fresh green salad. Enjoy your meal!