Place cubed potatoes in a pot of cold salted water, bring to a boil, and simmer for 15-20 minutes until fork-tender.
Drain potatoes and mash thoroughly with 1/4 cup butter and 1/4 cup heavy cream; season with salt and keep warm.
In a large mixing bowl, combine ground chicken, panko, egg, parmesan, minced garlic, oregano, salt, and pepper.
Divide the chicken mixture into 12 equal portions; insert one mozzarella pearl into the center of each portion and roll into a ball.
Heat 1 tablespoon of oil in a large skillet over medium heat; sear meatballs for 8-10 minutes until browned on all sides, then remove from pan.
In the same skillet, melt the remaining 1/4 cup butter and whisk in flour to create a roux; cook for 60 seconds.
Gradually whisk in chicken broth and the remaining 1/4 cup heavy cream, stirring constantly until the sauce thickens.
Return the meatballs to the skillet and simmer in the gravy for 5 minutes until the internal temperature reaches 165°F (74°C).
Plate a generous portion of mashed potatoes and top with three meatballs and a ladle of gravy.