Heat olive oil in a large skillet over medium-high heat.
Add ground beef to the skillet and cook, breaking it apart with a spoon, until browned and cooked through, about 5-7 minutes.
Add diced onion to the skillet and cook until softened, about 3-4 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.
Stir in dried oregano, dried basil, salt, black pepper, and crushed red pepper flakes.
Bring the mixture to a boil, then reduce heat to low and cover the skillet.
Simmer for 15 minutes, stirring occasionally, until the 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 and let it sit for 2-3 minutes to allow the cheese to melt.
Garnish with chopped fresh parsley before serving.