To make the spicy red sauce, heat olive oil in a large saucepan over medium heat, and cook and stir 1/2 cup of onion until softened, about 3-4 minutes. Stir in garlic, cook and stir until fragrant, another 3-5 minutes while avoiding burning.

Add oregano, chili powder, basil, salt, black pepper, cumin, cilantro, salsa, tomato sauce, tomato paste, and chicken broth. Stir until well-combined. Bring to a simmer, reduce heat to low, and stir often for 30 minutes until thickened slightly.

While sauce is simmering, cook ground beef in a large skillet over medium-high heat until browned evenly. Drain excess grease.

Add 3/4 cup onion, 1 tablespoon garlic, 1/2 teaspoon chili powder, and 1/2 teaspoon cumin to the beef. Cook and stir until onions soften and meat becomes aromatic, about 5-10 minutes. Add enchilada sauce and beef broth, simmer for 5 more minutes. Stir in shredded cheese until melted. Reduce heat to low and simmer for 30 minutes to thicken.

Preheat oven to 350°F (175°C). Lightly grease a 9x13-inch baking dish with cooking spray. Spray tortillas lightly with cooking spray and warm in the oven for 10 minutes.

Spread 1/2 cup of red sauce over the bottom of the baking dish. Fill each tortilla with meat mixture, reserving 1/2 cup of the meat for topping. Roll tortillas and place seam-side down into the dish. Top with remaining red sauce, reserved meat, and shredded cheese.

Bake enchiladas in preheated oven until cheese is golden and sauce is bubbly, about 30 minutes.