Combine minced meat, diced onion, and egg. Season with salt and pepper. Shape into small meatballs the size of the mini dumplings. Bring 2 liters vegetable stock to a boil in a large pot over medium-high heat. Reduce heat to low and simmer meatballs for 10-12 minutes until cooked through. Remove with a slotted spoon and set aside to keep warm.
In a pan, melt 80g butter over medium heat. Add 3 tablespoons flour and stir constantly for 2-3 minutes. In a separate bowl, mix 0.25 liters milk with 0.25 liters vegetable stock. Gradually pour this mixture into the flour mixture while stirring constantly. Simmer over medium heat for 5-7 minutes, stirring frequently, until the sauce is creamy and thickened. Season with salt, pepper, and grated nutmeg to taste. Add the corn and meatballs. Scatter frozen parsley over the sauce.
Cook the mini dumplings according to package instructions. Serve the dumplings alongside the meatballs in cream sauce.