Heat the vegetable oil in a large skillet over medium-high heat.
Add the chopped onion and cook for 3-4 minutes until softened.
Add the ground beef to the skillet and cook, breaking it up with a spoon, until browned and cooked through, about 6-8 minutes.
Stir in the minced garlic, ground cumin, chili powder, smoked paprika, salt, and black pepper. Cook for 1 minute until fragrant.
Pour in 1/2 cup of the enchilada sauce and stir to combine. Reduce heat to medium-low and simmer for 3 minutes.
Remove half of the beef mixture from the skillet and set aside in a bowl.
Add half of the corn tortillas to the skillet, spreading them evenly over the beef mixture remaining in the pan.
Spoon the reserved beef mixture evenly over the tortillas in the skillet.
Pour the remaining 1/2 cup enchilada sauce evenly over the beef and tortillas.
Sprinkle the shredded cheddar and Monterey Jack cheeses evenly over the top.
Cover the skillet with a lid and cook over low heat for 5-7 minutes, or until the cheese is melted and bubbly.
Remove from heat and let rest for 2 minutes.
Garnish with chopped cilantro and sliced jalapeño if using.
Serve warm with sour cream on the side.