Heat the olive oil in a large, deep-sided skillet over medium-high heat. Add the ground beef and diced onion, then season with salt and pepper. Cook for 5-7 minutes, breaking the beef into small pieces as it browns. Once the beef is cooked through and the onion is soft and translucent, drain off any excess grease.

Stir in the red pepper flakes and tomato paste. Cook for 1-2 minutes, stirring often, until the tomato paste darkens slightly. Add the minced garlic and dried thyme, then cook for about 30 seconds, just until the garlic becomes fragrant.

Stir in the Dijon mustard and Worcestershire sauce. Pour in the beef broth, scraping the bottom of the skillet to loosen any browned bits. Add the gnocchi and frozen peas and carrots, stirring until everything is evenly combined.

Cover the skillet and bring the mixture to a gentle simmer. Cook for 4-6 minutes, stirring once or twice, until the gnocchi is tender and the vegetables are heated through. If the sauce thickens too much, stir in a small splash of beef broth or water.

Turn the heat to low and pour in the heavy cream. Stir and cook for another 1-2 minutes, until the sauce is creamy and warmed through. Remove the skillet from the heat, then stir in the Parmesan until melted. Taste and add more salt and pepper as needed.

Serve warm with an extra sprinkle of Parmesan and a little dried thyme on top, if desired.