Melt some butter in the pan and add the meat. Cook to brown, breaking the meat up with some spatulas as it cooks. Add in the onions when it is halfway cooked.
When it is just about done, season with the salt, pepper, and garlic powder and stir to combine. Form a "patty" with the meat in a cooler area of the pan and use a food press to press the meat down for about 3-5 minutes to form the steak "patty"
While this is happening, add more butter to the pan and toast the bagels, cut side down, in the butter. Take the weight off the steak and add a slice of cheese to it.
I did this all on one large griddle but if you are using separate pans, get your egg pan ready and melt some butter in it. Whisk the eggs and add them to the pan. Season with salt. Cook like an omlette, basically letting the bottom solidify, then folding it over. Continue to fold to form a long rectangle the sides of the two sandwiches, then cut it in half to form the two squares, one for each sandwich.
Remove the bagels from the pan and top the bottom half of each with a slice of cheese. Add the steak "patty" on top of the cheese, then the egg. Drizzle on the hollandaise and serve.