Crispy fried onions: cut an onion into 4 quarters and slice thin slices off of two of the quarter pieces, making thin strips of onion. 

Add those thin strips of onion to a medium-sized bowl along with the buttermilk. You just need enough buttermilk so that the onion is submerged. Mix both together and add to the fridge to let the onion soak for 30 minutes to an hour. 

In another medium bowl add your all-purpose flour, salt, garlic powder, and ground black pepper. Mix thoroughly. 

After 30 minutes or so, remove the bowl with your onions and buttermilk from the fridge and place it beside the bowl with the flour. 

Add at least 1 inch of vegetable, peanut, or canola oil to a large pan or pot and place it over medium-high heat. While your oil is heating you can start dredging your onion pieces. grab a handful of onions in the buttermilk and shake off most of the liquid. Add to the bowl with the flour mixture and coat the onions well. Leave the onion pieces in the bowl with the flour until the oil is hot enough.

When the oil has risen to 350 degrees F (176 C) or when tiny pieces of flour sprinkled over the oil start to sizzle upon entry, you are ready to start frying.

Carefully remove some onions from the flour mixture and shake off excess flour. Add to the hot oil carefully and fry in batches for 2 to 3 minutes or until the onions turn a nice golden brown color.

Once any onions are cooked, move them carefully to a cooling rack or paper towels to rest while you fry the rest of your onions.

Beer cheese sauce: in a medium pot over medium heat add 3 tablespoons of butter and allow it to melt. Once the butter is melted, add 3 tablespoons of all-purpose flour and stir to ensure all of the flour is mixed in with the melted butter.

Cook for 2 minutes, stirring often. This gloopy, and pasty mixture of butter and flour that you've made is called a roux. 

Add beer to the flour and butter roux and whisk everything thoroughly until there are no lumps.

Add milk and bring the entire mixture to a boil. Reduce heat to medium-low and allow the liquid to simmer.

Add the salt, black pepper, and paprika to the mixture, stir and then slowly add shredded cheese, a handful at a time. Keep stirring to make sure everything gets combined and the cheese melts. Whisk often during this process.

Once all the cheese is added, reduce the burner heat to low and keep the cheese sauce warm until you are ready to serve. This beer cheese sauce will start to thicken as it cools, so keep it on low heat or move it to a warm crock pot if you want to keep it smooth and dippable for a long time.

Burger cooking and assembly: Slice your bun and toast the inside. You can either do this under a broiler or you can spread a tiny bit of butter on the bun and place it face down in the pan where you plan to cook your burger patties.

Heat a large skillet over medium high heat for at least 5 minutes. Shape your ground beef into 1 or 2 thin patties depending on whether you want a double or a single burger. Add your shaped patties to the hot skillet and season the patties with lots of salt and pepper. Cook the patties for 3 minutes on the first side and then flip. After one minute add the slices of Muenster cheese and cook for another 2 to 3 minutes on the second side. These patties should be thin, so they will cook quickly.

When the patties are fully cooked and the Muenster has started to melt slightly, remove the patties to a plate to rest. If you are making a double burger, you can go ahead and stack the patties. Add your slices of bacon to the hot skillet to warm through. They should be cooked already so they just need 30 or 45 seconds on each side to warm through. 

Add your burger patties with cheese to the bottom bun. Top the patty/patties with a couple of tablespoons of beer cheese sauce. Top the cheese sauce with bacon slices.

Sprinkle some crispy fried onion strings on top of the bacon and add 2 to 4 slices of pickles. 

Add and spread honey mustard onto the top bun and place the top bun on top of the burger, completing the sandwich.

Serve and enjoy.