Prepare and season the brisket: Trim the brisket and apply mustard or hot sauce as a binder. Season generously with a heavy pepper rub and let sit in the fridge for a few hours.
Smoke the brisket: Preheat your smoker to 220°F. Place the brisket in the smoker with a drip pan underneath. Smoke overnight for about ten hours or until the internal temperature reaches 165-170°F.
Rest the brisket: Remove the brisket from the smoker and wrap it to rest in a cooler for 2 hours.
Prepare the vegetables: While the brisket is resting, slice the onions and jalapeños. Cook them on a griddle with butter, salt, and pepper until soft and caramelized. Set aside.
Slice the brisket: Focus on using the meat from the point, as it has the most fat. Slice the brisket thinly.
Cook the brisket on the griddle: Place the sliced brisket on the griddle and cook until it has crispy edges and is well-rendered.
Combine ingredients: Add the onions and jalapeños to the griddle with the brisket. Mix in your favorite BBQ sauce and cook for a few minutes. Add shredded Jack and Gouda cheese and mix until melted and well combined.
Assemble the cheesesteaks: Form the cheesesteak mixture into piles and place hoagie buns on top. Toast the buns on the griddle before assembling.
Serve and enjoy: Remove the buns with the cheesesteak mixture and enjoy your delicious Smoked Brisket Cheesesteaks.