In a large skillet over medium heat, cook the bacon until crisp, 8 to 10 minutes. Set aside. Pour off any excess oil, leaving about 2 tablespoons in the skillet.
Put the flour and some salt and pepper in a resealable plastic bag and add the beef. Toss to coat the beef thoroughly. Heat the bacon grease in the skillet over medium-high heat. Add the beef to the skillet in 2 batches and brown on all sides, 4 to 5 minutes per batch. Set aside.
Put the onions in the bottom of a slow cooker. Add the beef, mushrooms, carrots, potatoes, garlic and jalapeno. Season with a big pinch of salt and some black pepper. Cut the bacon into large pieces and sprinkle them over the top.
Pour the beer into a pitcher, whisk in the tomato paste and Worcestershire and then pour it over the vegetables. Add enough beef broth to just cover the meat and top with the parsley and rosemary sprigs. Cover and cook on low for 6 hours.
Serve with Buttery Lemon Parsley Noodles and garnish with about 1 teaspoon of parsley per portion.
Buttery Lemon Parsley Noodles:
Bring a large pot of water to a boil. Cook the pasta according to the package instructions. (If using angel hair, stop just short of the al dente stage.) Drain and set aside.
Melt the butter in a large skillet over medium-high heat, then add the olive oil. Add the parsley, garlic and lemon zest and stir. Throw in the drained pasta and cook, tossing and coating it in the mixture, so that a few of the pieces get a little bit of a pan-fried texture to them, 2 to 3 minutes. Add the lemon juice and some salt and pepper and toss again.
If the stew is fatty, carefully remove the vegetables and meat. Strain the liquid and skim off any fat, then return the meat and vegetables to the gravy.