In a large pot add potatoes. Add enough water to cover potatoes. Place on stove burner over medium-high heat.
Preheat oven to 400degF. In a bowl, combine beef, pork, and bread crumbs. Form into 1½ inch balls and line up on parchment paper lined baking sheet. Bake for 15 minutes.
In a large saute pan over medium-high heat, add 2 tablespoons of butter. Once melted add mushrooms, salt and pepper. Stirring frequently, cook until mushroom begin to tender. Add remaining butter and flour. Stir for 3 minutes then add Marsala wine. let come just to a boil then add broth. Again, bring just to a boil while stirring. Reduce heat to medium.
Remove meatballs from oven and add to mushroom gravy in saute pan. Let simmer until ready to serve.
Drain potatoes in colander and return to pot. Add remaining potato ingredients and mash together.
Add a portion of potatoes to a shallow bowl. Then ladle meatballs and mushroom gravy over top.