Preheat oven to 400 degrees F. Add potatoes to a pot of cold water. Place over high heat and bring to a boil. Cook for 10 to 15 minutes, until potatoes are tender.
Meanwhile, heat a large skillet over medium heat. In a large bowl, combine ground pork, egg, panko bread crumbs, 1 tsp. salt, pepper, allspice, thyme, rubbed sage and garlic powder. I use my hands for this step. Add olive oil to skillet then the ground pork mixture. Break up with a wooden spoon and cook until no longer pink.
Sprinkle pork with flour and stir until coated. Cook another minute to cook out the flour taste. Add beer to the skillet and cook until it thickens. Add beef stock and Dijon and cook again, stirring often, until thickened to a gravy consistency. Pour into an 8x8 pan and spread evenly. Set aside.
Once potatoes are tender, drain well. Return them to the dry pot and mash. Add butter and allow to melt. Stir in milk and 3/4 cup kosher salt. Drop mashed potatoes in blobs over the ground pork mixture. Using a spatula, smooth the potatoes until the pork is covered. Bake for 20 to 25 minutes, until bubbly and potatoes start to turn golden.