Step 1: Heat olive oil in a large skillet or Dutch oven over medium-high heat. Add the ground beef and cook, breaking it up with a spoon, until browned and no longer pink. Drain off any excess fat.
Step 2: Push the browned ground beef to one side of the skillet. Add the chopped onion to the other side and sauté for 5-7 minutes until softened and translucent. Add the minced garlic during the last minute of cooking the onion, stirring until fragrant.
Step 3: Stir the ground beef, onion, and garlic together. Pour in the diced tomatoes (with their juice), tomato sauce, and beef broth. Add the dried oregano, dried basil, and red pepper flakes (if using). Stir everything well to combine.
Step 4: Bring the mixture to a simmer, then reduce the heat to low, cover, and let it cook for at least 20-25 minutes, stirring occasionally. This allows the flavors to meld beautifully. Season with salt and pepper to taste.
Step 5: Remove from heat and let it rest for a few minutes. Garnish generously with fresh chopped parsley before serving hot.