1) Preheat oven to 350 degrees. Lightly coat a 9X 13" baking dish with cooking spray. (I usually need one of these as well as another half-size one.)
2) Cook chicken breasts by boiling on medium (about 15 minutes) or baking in a covered dish until no longer pink inside. Let them cool slightly and then shred using forks. Set aside.
3) Lightly coat a large (deep!) skillet with cooking spray and place over med-high heat. Add green onions, cilantro, and jalepeno. Saute for 2 minutes. Add shredded chicken and 1 can (or half a big can) of enchilada sauce. Cook, stirring occasionally, until heated through, about 5 minutes.
4) Pour the 2 remaining cans of enchilada sauce in a medium bowl and microwave until warm, about 2 minutes. Dipe each tortilla in the heated sauce and fill with about 1/8 of the chicken mixture. Roll up and place, seam-side down, in th prepared baking dish. (they break veeery easily, but don't be sad- just sprinkle extra cheese over the broken parts in the next step, and no one will ever know! :) )
5) Pour remaining heated sauce over enchiladas and sprinkle with cheese. Bake uncovered until enchiladas are heated through and the cheese is melted. (about 15 minutes.)
6) Divide lettuce onto four plates and place a portion of enchiladas on top. Top enchiladas with a spoonful of salsa, a dollop of sour cream, a sprinkle of tomatoes and olives. Enjoy! :)