For green sauce: Heat oil in a 25 cm skillet over medium heat. Cook onion, roasted* poblano chilies, jalapeno chili and garlic in oil for about 8 minutes, stirring occasionally, until onioin is tender. Stir in whipping cream and salt. Set aside.
For casserole: heat oil in a 25 cm nonstick skillet until hot. Cook tortillas strips in oil for 30 to 60 seconds or until light golden brown; drain. Heat oven to 350. Grease a 2 litre casserole dish. Layer half of the tortilla strips in the bottom of casserole. Top with chicken, half of the New Mexico Green Sauce (about two third cup) and 1 cup of the cheese. Gently press layers down into casserole. Repeat with remaining tortilla strips, sauce and cheese. Bake uncovered about 30 minutes or until cheese is melted and golden brown.
* To roast chilies, set oven to broil. Broil whole chilies with tops about 13 cm from the heat for 5 to 7 minutes, turning occasionally, until skin is blistered and evenly browned (not burned). Remove chilies to a plastic bag and closetightly; let stand for 20 minutes, then peel.