Prepare the beef mixture: In a mixing bowl, combine ground beef, BBQ sauce, black pepper, oregano, garlic powder, rosemary, thyme, and red pepper flakes. Mix gently until just combined, avoid over-mixing to keep the burgers tender.
Form the patties: Divide beef mixture into 4 equal portions. Roll each into a ball (about 4 oz each). Do not flatten yet, smash burgers get their shape in the pan.
Cook the burgers: Heat a cast-iron skillet or griddle over medium-high heat until very hot. Place a beef ball onto the skillet, then use a heavy spatula or burger press to smash it flat to about 1/2 inch thick. Cook for 2-3 minutes, until the edges are crispy and caramelized. Flip, cook another 2 minutes, and brush lightly with extra BBQ sauce. If adding cheese, place a slice on top after flipping and cover pan briefly to melt.
Assemble: Toast burger buns, then place a patty on each bun. Add desired toppings and an extra drizzle of BBQ sauce.
Serve: Enjoy hot, with fries, coleslaw, or grilled veggies on the side.