Heat olive oil in a large skillet over medium-high heat.
Add ground beef and cook, breaking it up with a spoon, until browned and cooked through, about 5-7 minutes.
Add diced onion to the skillet and cook until softened, about 3 minutes.
Stir in minced garlic and cook for 1 minute until fragrant.
Add orzo pasta to the skillet and stir to combine with the beef mixture.
Pour in diced tomatoes with their juice and beef broth.
Add dried oregano, dried basil, salt, black pepper, and crushed red pepper flakes. Stir well.
Bring the mixture to a boil, then reduce heat to low. Cover and simmer for 15 minutes, or until orzo is tender and most of the liquid is absorbed.
Remove the skillet from heat and sprinkle shredded mozzarella cheese evenly over the top.
Cover the skillet again and let it sit for 2-3 minutes until the cheese melts.
Garnish with chopped fresh parsley before serving.