Step 1

Preheat oven to 375 degrees F (190 degrees C). Spray a 9x13-inch baking pan with cooking spray.

Step 2

Cook ground beef and onions in a skillet over medium heat until beef is browned, 7 to 10 minutes; drain grease. Stir in water and taco seasoning; cook, stirring often, until thickened, about 2 minutes. Add refried beans, salsa, olives, and green chiles. Cook and stir over low heat until ingredients are warmed through, 3 to 4 minutes.

Step 3

Place half of the taco shells in the bottom of the baking dish. Pour in half of the ground beef mixture; sprinkle with half of the Cheddar cheese. Repeat with remaining taco shells, ground beef mixture, and Cheddar cheese.

Step 4

Bake in the preheated oven until cheese is melted and bubbly, 20 to 25 minutes.