Heat the oven to 375°F. (See note to skip this step)
Heat a large heavy-bottom, non-stick skillet with lid over medium high heat. Add 1 tablespoon oil, the onion, and the ground beef. Sprinkle with 1 teaspoon of the salt, garlic, black pepper, and the smoked paprika.
Break the meat apart with a spoon and cook for 5-8 minutes until the meat is browned and cooked through and the onion has softened, stirring occationally.
Remove the meat and set aside. To the same pan (no need to wash it first) add 1 tablespoon of the olive oil and the potatoes. Sprinkle with 1 teaspoon of the salt. Cook on medium to medium-high for 1 minute until the spices are fragrant.
Add ¼ cup water, cover, and cook, stirring frequently, until the potatoes are just tender but not falling apart, about 15-20 minutes. Note: if the potatoes begin to stick to the bottom of the pan, add additional water, ¼ cup at a time.
When the potatoes are cooked through, add the cooked meat back to the pan, along with the mustard, Worcestershire sauce, and ketchup, stirring to combine. If the pan seems dry, add an additional ¼ water, stirring to combine.
Sprinkle half the cheese over the beef and potato mixture, stirring to combine. Sprinkle the remaining cheese evenly over the top, then place in the oven for 5 minutes, or until the cheese melts. Serve warm with toppings of choice.