Season the brisket all over with the paprika, garlic powder, salt and pepper. Place it in your slow cooker and cover it with the beer. Cook on low for 8 hours.
When finished, if the brisket is still in one piece, remove it and place it on a cutting board. Use a sharp knife and a fork to shred the brisket (you can also do this in the slow cooker) and then place it back in the cooker for another 30 minutes or so on low. It should combine with the juices and soak some of them up. You also may need to toss the beef a few times in the crockpot.
To assemble the sandwiches, preheat the oven to 325 degrees F. If you have just prepped the pretzel buns, it will already be on! Spread some of the honey mustard mayo on the bottom of your bun. Top with the brisket, then a slice of havarti cheese.
Stick the sandwiches in the oven for 5 to 6 minutes, just until the cheese melts. Remove the sandwiches and top with a handful of microgreens or arugula. Top with your everything pretzel bun and serve!