In a large bowl, combine ground beef, ground pork, egg, breadcrumbs, salt, garlic powder, Italian seasoning, and pepper. Mix until combined.
Make 1 1/4-inch meatballs with the mixture.
Heat olive oil in a large skillet over medium-high heat. Brown the meatballs for about 5 minutes, working in batches if needed. Set them aside once browned.
In the same skillet, reduce heat to medium and add butter. Stir in flour and cook for a few minutes to thicken. Gradually whisk in broth.
Add Worcestershire sauce, onion powder, sage, salt, and pepper. Stir to combine.
Return the meatballs to the skillet and allow the gravy to simmer for about 10-12 minutes or until the meatballs are cooked through.
Adjust seasonings and remove from heat once the gravy is thick. Garnish with fresh parsley, and serve hot.