Preheat oven to 375°F. Coat a 9x13-inch baking pan with canola cooking spray.
Add shredded chicken, green onions, and shredded cheese to a large mixing bowl and toss well to blend.
One by one, heat tortillas in a nonstick frying pan until softened. Lay a heaping 1/3 cup of chicken down the middle of each tortilla. Add 1 1/2 teaspoons of fat-free half-and-half down the center of each. Roll up the tortillas and place seam-side down in the prepared pan.
Bake for about 25 minutes. Pan can be covered or uncovered – it works both ways.
To make the verde sauce, add tomatillos, cilantro, and green chilies to a food processor and pulse briefly (the texture should be somewhat chunky, not pureed). Stir in the sour cream. Serve the enchiladas with a spoonful of verde sauce over the top.