Bring a pot of water to a boil. Add a generous amount of salt, then the pasta and cook spaghetti until al dente according to package directions.
Heat a deep skillet over medium-high heat. Add EVOO and bacon. Brown and crisp bacon, about 5 minutes, then remove with a slotted spoon to a paper towel-lined plate and reserve. Drain off a little excess fat if necessary but leave just enough to coat the bottom of the skillet. Add the sirloin and crumble it with a wooden spoon as it browns, 3-4 minutes. Add the onions and garlic, and season with salt, pepper, hot sauce, Worcestershire, chili powder and cumin. Cook for another 5-6 minutes. Add the beer, cook for 1 minute more then add tomatoes and tomato sauce. Bring up to a bubble and continue to cook for 5 minutes.
While the meat sauce is cooking, make the cheese sauce: Heat a small sauce pot over medium heat and add butter. When the butter melts, stir in the flour and cook for 1 minute. Whisk in the chicken stock and then the milk. Thicken for 2 minutes then stir in the cheese and melt, for another 2 minutes. Stir in the jalapenos and scallions. Season with a little salt and pepper.
Drain spaghetti, add to the meat sauce and combine.
Pour into a large serving bowl and pour the cheddar cheese sauce over the top.