Heat a large skillet over medium heat. Add 1 lb ground beef and 1 finely diced onion. Cook for 6-8 minutes, breaking up the beef, until browned and softened. Add 2 minced garlic cloves and cook for 1-2 minutes.
Stir in 1 tbsp tomato paste, salt, black pepper, and ½ tsp red pepper flakes (if using). Cook for 1-2 minutes to enhance flavor.
Pour in 1 (14 oz) can crushed tomatoes and 2 ½ cups beef broth. Stir to combine and bring to a simmer.
Add 1 ½ cups orzo to the skillet, reduce the heat to medium-low, and cover. Cook for 10-12 minutes, stirring occasionally, until the orzo is tender and most of the liquid is absorbed.
Stir in 1 cup heavy cream and let simmer for 2-3 minutes until creamy. Adjust seasoning as needed.
Sprinkle ½ cup grated Parmesan cheese over the dish and garnish with fresh basil. Serve warm.