In a medium bowl, combine ground beef, panko breadcrumbs, egg, Worcestershire sauce, garlic powder, salt, and pepper. Mix gently until just combined; avoid overmixing. Form into approximately 1-inch meatballs.

Heat olive oil in a large skillet or Dutch oven over medium-high heat. Add meatballs and brown on all sides, working in batches if necessary to avoid crowding the pan. Remove meatballs from the skillet and set aside.

Add sliced mushrooms and minced garlic to the same skillet. Sauté for 3-5 minutes until mushrooms are softened and lightly browned.

Sprinkle flour over the mushrooms and garlic. Cook, stirring constantly, for 1 minute to toast the flour.

Gradually whisk in the beef broth, ensuring no lumps form. Bring the mixture to a simmer.

Stir in the condensed cream of mushroom soup until well combined. Return the browned meatballs to the skillet. Reduce heat to low, cover, and simmer for 15-20 minutes, or until meatballs are cooked through and the gravy has thickened.

Taste and adjust seasoning if needed. Garnish with fresh chopped parsley before serving.