Place the breadcrumbs and milk in a large bowl and mix well to combine. Set aside for 5 minutes. Add ground beef, egg and seasoning. Mix just until combined, using your hands. Roll the meat into 2 tablespoon-size balls.
In a large non-stick skillet, heat the butter and 1 tbsp olive oil over medium heat. Add the meatballs and brown on all sides, about 8-10 minutes, turning them 2-3 times. Transfer to a plate.
In the same skillet, heat 2 tbsp oil over low heat. Add onion and garlic, cook for 2-3 minutes until soft. Add orzo and cook for 1 minute. Pour the chicken broth. Bring to a boil over high heat and cook, stirring often, about 12 minutes.
In the meantime, make the pesto. Place feta, pine nuts, green olives, olive oil, lemon juice, salt and pepper in your food processor. Pulse until just combined. Add basil and process very briefly, just until combined.
Add feta pesto to orzo and slide the meatballs back into the skillet. Cook until warmed through.
Serve orzo topped with meatballs, pine nuts, chopped olives and crumbled feta. Sprinkle some red pepper flakes. Enjoy!