Bring a large pot of water to a boil.
Saute the onion over medium heat until tender and season with salt. Add the garlic and cook for a minute longer.
Add the beef, oregano, and cayenne. Season generously with salt and pepper. Brown the beef and stir to break it up into smaller pieces. Drain the fat from the pan and discard.
Sprinkle the flour over the beef and stir until well mixed. Stir in the tomatoes and stock. Raise the heat to medium high and bring to a boil. Simmer over medium heat for 10 minutes.
Wile the beef simmer, add the macaroni and 1 teaspoon salt to the boiling water. Cook a minute less than directed on the packaging and drain well.
Stir the macaroni and half the cheese into the beef mixture. If it looks too thick add in a bit more stock.
Divide among serving bowls and top with parsley and the remaining cheese.