Heat olive oil in a large deep skillet or 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. Drain excess fat if necessary.
Add the minced garlic to the beef and cook for 1 minute until fragrant, stirring constantly to avoid burning.
Pour in the beef broth and add the uncooked spaghetti pasta. Press the pasta down gently to submerge it in the broth.
Bring the mixture to a boil, then reduce heat to medium-low. Simmer uncovered, stirring occasionally, until the pasta is cooked al dente and most of the liquid is absorbed, about 10-12 minutes.
Stir in the unsalted butter, salt, black pepper, and crushed red pepper flakes until the butter is melted and the sauce is creamy.
Remove from heat and stir in the grated Parmesan cheese until well combined.
Garnish with chopped fresh parsley before serving.