Cook The Beef In A 10-Inch Skillet Over Medium Heat Until It'S Well Browned, Stirring Often To Separate Meat. Pour Off Any Fat. Stir The Picante Sauce And Chili Powder In The Skillet. Layer4 Tortillas In A 2-Quart Microwave-Safe Shallow Baking Dish. Top With Half Of The Meat Mixture And Half Of The Soup. Repeat The Layers. Top With The Cheese. Cover The Dish. Microwave At 70% Power For 8 Minutes Or It'S Until Hot And Bubbling. Serve With Sour Cream, If Desired.