Heat the olive oil in a large pot over medium-high heat.
Add the ground beef and cook, breaking it up with a spoon, until browned and cooked through, about 5-7 minutes.
Add the chopped onion to the pot and cook until softened, about 3 minutes.
Stir in the minced garlic and cook for 1 minute until fragrant.
Pour in the beef broth and bring to a boil.
Add the uncooked pasta, salt, black pepper, dried oregano, and crushed red pepper flakes to the pot.
Reduce the heat to medium-low and simmer, stirring occasionally, until the pasta is tender and most of the liquid is absorbed, about 12-15 minutes.
Remove the pot from heat and stir in the unsalted butter and grated Parmesan cheese until melted and well combined.
Taste and adjust seasoning if needed before serving.