Preheat the oven to 375 degrees F.
Put the Beef Stew with Beer and Paprika in a 10-inch skillet or baking dish. Spoon the Horseradish Mashed Potatoes all over the surface of the stew and use a spoon or spatula to spread them out. Bake until the top is golden brown, 40 to 45 minutes.
Heat the oil and butter in a large pot over medium-high heat. Brown the meat in 2 batches, 2 to 3 minutes per batch; set aside on a plate.
Add the onions to the pot. Stir and cook until softened, 2 to 3 minutes, then add the garlic and cook for another minute. Add the flour and stir to coat the onions and garlic. Pour in the beef stock, beer and a splash of water, then add the tomato paste, Worcestershire, sugar, paprika, salt and some pepper. Add the beef back to the pot and stir to combine. Cover and simmer until the beef is cooked and the mixture has thickened, 1 1/2 to 2 hours. Top with the parsley if using.
Note: The liquid should cook down to a thicker state. If it gets too thick/reduces too much, add water as needed.
Bring a large pot of water to a simmer and add the potatoes. Bring to a boil and cook until fork-tender, 20 to 25 minutes.
Drain the potatoes in a large colander. Put them back into the dry pot and put the pot on the stove. Mash the potatoes over low heat, allowing all the steam to escape before adding in the other ingredients.
Turn off the heat and add the butter, cream cheese, heavy cream, horseradish cream, seasoned salt, kosher salt and pepper. Mash to combine. Add the chopped parsley and mix in.