Heat the EVOO in a large skillet over medium to medium-high heat. Add the guanciale, and cook to render the fat, 2 to 3 minutes. Season with black pepper, and then add the garlic, onions and bay leaf and cook until the onions are soft and sweet but not brown. Add the wine and reduce by half, then add the Beef and Tomato Base. Cool and store for a make-ahead meal.
When ready to serve, reheat over medium heat and remove the bay leaf before serving.
Bring a large pot of salted water to a boil for the bucatini, and cook the pasta to al dente. Reserve a cup of the starchy cooking liquids. Drain the pasta, and return it to the pot with the butter and half of the reheated sauce. Toss with the cheese to combine, and serve in shallow bowls. Top with additional sauce and cheese.
Beef and Tomato Base:
Heat the oil in a large pan over medium-high heat. When the oil is very hot, pat the meat dry with paper towels and add half of the beef to the pan. Crumble the beef with a potato masher or wooden utensil. Cook to develop a deep brown color, season with salt and pepper, and then remove to a plate. Repeat the process with the remaining beef. Add the tomato paste to the pan and stir until fragrant. Then add the stock and the browned beef. Stir to combine, then reduce the heat to a simmer.