In a large mixing bowl, combine the ground beef, minced garlic, breadcrumbs, egg, ketchup, yellow mustard, Worcestershire sauce, salt, pepper, and parsley. Mix gently.

Scoop out portions of the meat mixture and roll them into 1.5-inch meatballs, aiming to make about 24 to 26 meatballs.

Heat 2 tablespoons of olive oil in a large skillet over medium-high heat. Add the meatballs in batches, cooking each side for about 2 minutes until golden brown. Transfer to a plate.

In the same skillet, reduce heat to medium and add 2 tablespoons of unsalted butter. Add diced yellow onion and sauté for about 15 minutes until soft and golden brown.

Pour in the chicken and beef broth along with the beef bouillon cube, onion powder, garlic powder, dried parsley, and smoked paprika. Stir well and bring to a gentle boil.

Mix together 2 tablespoons of cornstarch with 2 tablespoons of cold water until smooth. Slowly pour into the boiling gravy while stirring to prevent lumps. Cook for an additional 2-3 minutes until thickened.

Once thickened, return the browned meatballs to the skillet. Reduce heat to low and simmer for about 10 minutes.