Preheat oven to 350°F (175°C).

In a large skillet, cook ground beef, chopped onion, and minced garlic over medium heat until beef is browned and onion is translucent; drain off any excess fat.

Stir in taco seasoning mix and cook for 5 minutes, stirring constantly.

Prepare enchilada sauce according to package directions.

Pour 1/4 cup of enchilada sauce into the bottom of a greased 13x9 inch baking dish.

Place an equal amount of ground beef mixture onto each flour tortilla.

Sprinkle grated Mexican blend cheese and black olives over the beef.

Reserve about 1 cup of cheese for the top.

Roll each tortilla tightly and place seam-side down in the baking dish over the sauce.

Drizzle the remaining enchilada sauce evenly over the enchiladas.

Sprinkle the remaining cheese over the top.

Bake in the preheated oven for 20-25 minutes, or until cheese is melted and bubbly and the enchiladas are heated through.