Preheat oven to 350°. In a medium bowl combine ground meat, rice, egg, rosemary, about half of the parsley, fennel, and 1/2 tsp salt, and 1/4 tsp pepper. Mix gently to combine. Form into 8 meatballs.
Heat olive oil in a Dutch oven over medium heat. Add meatballs and cook for 2-3 minutes per side until well browned. Remove to a plate.
Without wiping out the pan add cabbage and carrots with a heavy pinch of salt and pepper and toss together. Cook, undisturbed, for 5-6 minutes until charred in places and slightly softened. Stir in flour and cook for 1 minutes while stirring. Mix in beer, stock or broth, and white pepper and bring to a simmer. Reduce heat to maintain a low simmer and cook, stirring occasionally, for about 3-4 minutes until just slightly thickened. Remove from heat.
Add meatballs to the pan and cover. Transfer to oven and bake for 40 minutes.
Meanwhile, heat a large pot of salted water over high heat. When boiling add potatoes and cook for 15-20 minutes until very tender. Drain and return to pot. Mash potatoes to desired consistency. Stir in butter and 1/4 cup of milk. Add more milk as needed and season with salt and pepper to taste.
Divide mashed potatoes amongst plates or bowls and top with stew. Sprinkle remaining parsley over the top.