Preheat oven to 400°F. Spray a 13 x 9-inch casserole dish with nonstick spray.
2
Place taco shells standing up in the baking dish.
3
Preheat olive oil in a skillet over medium heat. Add ground chicken and onion. Cook until chicken is done and onion is tender, about 8 to 10 minutes. Remove any excess grease and liquids.
4
Add taco seasoning mix, drained diced tomatoes, and olives to the skillet. Stir to combine with the chicken. Continue to cook 5 minutes, stirring frequently.
5
While the taco meat is cooking, place the shells in the oven and bake for 5 minutes to warm and crisp.
6
Remove the shells from the oven and fill each one with the chicken taco meat mixture, dividing evenly between each of the shells. Top with shredded cheese.
7
Bake for 5 to 10 minutes or until the cheese is melted and the shells are turning golden brown.