Heat olive oil in a large skillet over medium-high heat.
Add the ground beef and cook, breaking it apart with a spoon, until browned and cooked through, about 5-7 minutes.
Add the diced onion and minced garlic to the skillet with the beef and cook until the onion is translucent, about 3 minutes.
Sprinkle the flour over the beef mixture and stir well to combine. Cook for 1 minute to remove the raw flour taste.
Pour in the beef broth and milk, stirring constantly to avoid lumps.
Add the uncooked elbow macaroni, salt, black pepper, and smoked paprika. Stir to combine.
Bring the mixture to a boil, then reduce heat to medium-low and cover the skillet.
Simmer for 12-15 minutes, stirring occasionally, until the macaroni is tender and most of the liquid is absorbed.
Remove the skillet from heat and stir in the shredded cheddar and mozzarella cheeses until melted and creamy.
Serve hot, garnished if desired.