Preheat the oven to 325 degrees F.
Heat the olive oil in a large skillet. Add the onions and salt. Cook over medium-low heat, stirring occasionally, for 8 to 10 minutes, until the onions are translucent but not brown. Stir in the hungarian paprika and cumin and cook for another minute or two, until fragrant. Off the heat, add the Worcestershire sauce, chicken stock, and tomato paste. Allow to cool slightly.
In a large bowl, combine the ground chuck, onion mixture, bread crumbs, and eggs, and mix with your hands. Shape the mixture into a rectangular loaf on a sheet pan covered with parchment paper or foil.
In a small mixing bowl, combine the ketchup with the remaining paprikas and cayenne. Slather the ketchup over the tops and sides of the loaf.
Bake in the oven for 1 to 1 1/4 hours, until the meatloaf is cooked through. (A pan of hot water in the oven, under the meatloaf, will keep the top from cracking.) Allow to rest for 10 minutes. Then serve alongside smashed potatoes