Heat a large skillet or Dutch oven over medium-high heat. Add the ground beef and cook for about 8-10 minutes, breaking it apart until no longer pink. Drain excess fat if necessary.

Stir in the diced onion and minced garlic to the browned beef. Cook for 4-5 minutes until the onion becomes translucent. Add Worcestershire sauce, thyme, salt, and pepper, stirring to combine.

Sprinkle the flour over the beef mixture, stirring constantly for about 1-2 minutes. Gradually pour in the beef broth while mixing continuously until the gravy thickens, about 3-5 minutes. Reduce heat and let simmer.

In a separate bowl, whisk together the all-purpose flour, baking powder, and a pinch of salt. Cut in cold butter until it resembles coarse crumbs. Stir in milk until just combined.

Spoon the dumpling mixture over the simmering beef mixture. Cover the pan with a lid and reduce the heat. Allow the dumplings to steam for about 15 minutes.

Remove from heat and let sit for a couple of minutes. Garnish with parsley if desired and serve warm.