Bring a large pot of water to a boil for the pasta. Salt the water and cook the pasta shy of al dente, 5 to 6 minutes.
While the water comes to a boil, heat the EVOO in a Dutch oven or deep skillet over medium-high heat. Add the bacon and crisp. Remove the bacon with a slotted spoon and remove some of the drippings, leaving a thin layer. Add the beef, brown and crumble, but leave a few larger pieces. Season with salt and pepper. Once the beef has caramelized, add the onions and cook to tender. Add the stock and Worcestershire, then reduce the heat to low.
In a saucepot over medium to medium-high heat, melt the butter. Whisk in the flour, cook 1 minute. Whisk in the milk and season with salt and pepper. Thicken to coat the back of a spoon. Stir in the cheese. When the cheese has melted into the sauce, stir in the mustard, ketchup, relish and hot sauce. Combine the pasta with the sauce and fold in the meat. Place in a large casserole dish. Cool and store for a make-ahead meal.
To serve, preheat the oven to 375 degrees F. Bring the casserole to room temp then bake until brown and bubbly on top and golden at edges, 45 to 50 minutes.
Recipe courtesy of Rachael Ray