In a large glass measuring cup or small bowl, combine the panko breadcrumbs and the cream. Stir to combine and then let rest for 5-10 minutes, until the cream is absorbed. In a large skillet over medium high heat, saute the onions with the butter for about 5 minutes.
While the onion is cooking, place the meat in a large mixing bowl and break it up with your hands. Add the egg, spices, and the breadcrumbs and cream mixture. Add the onions and stir with a wooden spoon or your hands to gently combine. Form into small balls. I used a 1" scoop to make them uniform, and then set aside.
Preheat the oven to 350 degrees. Wipe out the skillet that you cooked the onions in and add 2 tablespoons of butter. Heat over medium high. When the butter has melted, add the meatballs in batches. The skillet should be hot enough that they sizzle when they contact the pan. I used tongs to place the meatballs into the hot pan and then two forks to turn them side to side. Brown the meatballs on all sides and then transfer to a large baking sheet lined with aluminum foil.
When all of the meatballs have been browned, place the baking sheet in the preheated oven. Bake for 10 minutes. If you cut a meatball in half, it should not be pink. The interior temperature should be 170 degrees.
While the meatballs are baking, heat a small saucepan over medium to medium low heat. Melt the butter and add the flour. Whisking constantly, cook for about a minute, being careful not to let it brown. Once it combines, add the stock and whisk well. Bring to a simmer and let it thicken, this should only take a couple minutes. Add the cream and heat through.
Remove from the heat and season with soy sauce, salt and pepper. Taste and adjust the seasonings. Add the parsley and nutmeg, taste again and adjust as needed. Drizzle sauce over the meatballs right before serving. Enjoy!
If you aren't familiar with cooking things in batches, here is a tip. Start placing your meatballs in the pan, at the outer edge, next to the handle. Go clockwise around the pan and then fill in the middle. It is easy to remember which ones have cooked the longest that way and by the time you fill in the middle, it is time to start flipping them over and continue around the circle again.I used a food processor to get the onions to an extremely fine mince. The smaller the pieces, the better the meatballs will hold together. The meatballs can be formed in advance and then refrigerated until you are ready to brown and bake them right before dinner.