Heat the oil in a saucepan over medium-high heat, add the yellow onion. Cook until soft, add the ground beef. Cook the meat until browned, drain the fat. Add the garlic powder, chili powder, paprika, cumin, salt, and pepper and stir well. Add the water and stir. Reduce the heat to low and simmer for about 20 minutes.
To build the nachos, place a layer of patacones on an oven proof dish. Top with a layer of beef, then half of the cheddar cheese and half of the Monterey Jack cheese. Add another layer of patacones, another layer of beef, and the rest of the cheese.
Place the patacones nachos in the oven at 325 degree until the cheese is melted. Top with tomatoes, sliced jalapeño, red onion, cilantro, guacamole and sour cream.