Melt two tablespoons butter and cook onions and green pepper in it until softened. Remove to a bowl. Stir chopped chicken and green chilis into onion-pepper mixture. Melt remaining 3 tablespoons of butter. Blend in flour and seasonings. Whisk in chicken broth. Cook, stirring, until sauce boils. Remove from heat; stir in sour cream and half cup cheese. Stir half cup sauce into chicken mixture. Dip each tortilla in remaining hot sauce to soften and spoon chicken mixture into center of tortilla. Roll up and arrange in 13 x 9 x 5 cm pan; repeat with all tortillas. Pour remaining sauce over tortillas. Sprinkle with remaining cheese. Bake uncovered at 180ºC or about 25 minutes.