Heat a large skillet over medium-high heat and add the ground beef.
Cook the beef, breaking it apart with a spatula, until it begins to brown, about 4-5 minutes.
Add the chopped onion and minced garlic to the skillet with the beef. Cook until the onion is softened, about 3 minutes.
Stir in the ground cumin, chili powder, smoked paprika, salt, and black pepper.
Pour in 1/4 cup water and stir to combine. Reduce heat to medium and cook until the beef mixture is fully cooked and the water has mostly evaporated, about 5 minutes. Remove from heat.
Heat 1/2 tablespoon olive oil in a clean large skillet over medium heat.
Place one tortilla in the skillet and sprinkle 1/2 cup shredded cheddar cheese evenly over half of the tortilla.
Spoon about 1/4 of the ground beef mixture over the cheese, then sprinkle 1 tablespoon chopped cilantro on top.
Sprinkle another 1/4 cup shredded cheddar cheese over the beef, then fold the tortilla in half to cover the filling.
Cook for 3-4 minutes until the bottom is golden brown and the cheese starts to melt.
Carefully flip the quesadilla and cook the other side for another 3-4 minutes until golden brown and cheese is fully melted.
Remove from skillet and let rest for 1 minute before slicing into wedges.
Repeat the process with the remaining tortillas and filling, adding more olive oil to the skillet as needed.
Serve warm with your favorite salsa or sour cream if desired.