In a medium bowl mix together one can of green enchilada sauce, sour cream, milk and onion. Mix until blended.
Preheat oven to 350°(F) degrees.
In a small sauce pan, add ½ inch of vegetable oil and heat over medium-high heat.
Flash-fry each tortilla for 5–10 seconds and place on a paper towel-lined plate. Use caution when frying in hot oil! Place a good-sized pinch of cheese down the middle of each tortilla. Follow with two tablespoons of shredded chicken.
Starting from the outer edge of one side of the tortilla fold over the chicken and cheese and roll to the other edge of the tortilla.
Place seam side down in a 9 x 13 baking dish.
Continue filling tortilla's until they are all filled and in the baking dish.
You may have to lay some of the enchiladas in the opposite direction to squeeze them all in, or use a second small baking dish.
Pour creamy enchilada sauce over the top of each enchilada.
Top with remaining cup of cheese. Sprinkle with chopped green onion.
Bake at 350° degrees for 30–40 minutes until cheese is melted and sauce is bubbly.
Serve immediately. Garnish with sour cream or salsa.