Preheat your oven to 350°F (175°C).
In a large skillet over medium heat, add the ground beef, diced onion, and minced garlic. Cook until the beef is browned, breaking it up with a spoon, for about 5-7 minutes.
Drain excess fat, then add chili powder, cumin, salt, and black pepper to the beef mixture. Stir well to combine and cook for an additional 2 minutes to allow the spices to bloom. Remove from heat.
In a mixing bowl, pour 1 cup of the enchilada sauce and mix with the beef mixture until well combined.
Warm the tortillas slightly in the microwave for about 20 seconds to make them pliable.
Spread a thin layer of enchilada sauce on the bottom of a 13x9 inch baking dish.
Take one tortilla, spoon about 1/4 cup of the beef mixture onto it, and roll it up tightly. Place the rolled tortilla seam-side down in the baking dish. Repeat with the remaining tortillas and beef mixture.
Once all the enchiladas are in the baking dish, pour the remaining enchilada sauce over the top, ensuring all tortillas are well covered. Sprinkle the shredded cheese evenly over the sauce.
Cover the baking dish with aluminum foil or a lid and bake in the preheated oven for 20 minutes. Remove the foil and bake for an additional 10 minutes, or until the cheese is bubbly and slightly golden.
Let the enchiladas cool for a few minutes before serving. Garnish with fresh cilantro and serve with sour cream if desired.