1/4 c. butter
1/4 c. all-purpose flour
2 c. regular strength chicken broth
1 c. unflavored yogurt
1/2 (7 oz.) can diced mild green chiles
12 (6 inch) corn tortillas
2 c. (about 9 oz.) bite-size pieces, cooked chicken
1 sm. onion, chopped
2 c. (8 oz.) shredded Jack cheese
1/4 c. thinly sliced green onions

In a 2-quart pan, melt butter over medium heat. Add flour and stir until bubbly. Whisk in broth; stir until boiling. Remove from heat; mix in yogurt and chiles. Cover the bottom of a 9x13 inch baking dish with 1/3 of the sauce. Top with remaining tortillas, sauce, and cheese. Cover and bake in a 400 degree oven until hot in center, 30 to 35 minutes. Sprinkle with green onion.