Make the blackened seasoning. In a small bowl, mix smoked paprika, kosher salt, black pepper, garlic powder, onion powder, dried thyme, dried oregano, cayenne pepper, and chili powder.
Form the patties. Divide the ground beef into 4 equal portions. Gently shape into burger patties slightly wider than your buns and press a small dimple into the center of each patty.
Season the patties. Coat both sides of each patty generously with the blackened seasoning. Press it lightly onto the outside so it sticks.
Preheat the smoker, optional. For a smoky version, set the smoker or pellet grill to 225°F using oak, hickory, pecan, or cherry wood.
Smoke the burgers, optional. Place the patties directly on the smoker grates and smoke for 20 to 30 minutes, or until the internal temperature reaches about 120°F to 130°F.
Preheat the grill or griddle. Heat a grill, griddle, or cast iron skillet to 450°F to 500°F for a hot sear.
Sear the patties. Place the patties on the hot cooking surface and sear for 2 to 3 minutes per side, until a dark blackened crust forms.
Add the Swiss cheese. During the last minute of cooking, place 1 slice of Swiss cheese on each patty and let it melt.
Cook to temperature. Continue cooking until each burger reaches 160°F internal in the thickest part.
Add blue cheese crumbles. Remove the patties from the heat and immediately top each one with crumbled blue cheese so it softens slightly.
Toast the buns. Butter the cut sides of the brioche buns and toast them on the grill, griddle, or skillet until golden brown.
Sauce the buns. Spread blue cheese dressing on the bottom bun and a little more on the top bun if desired.
Build the burger. Place the blackened Swiss-covered patty on the bottom bun. Add the softened blue cheese crumbles, bacon or onions if using, and any extra toppings you like.
Finish and serve. Add the top bun and serve immediately while the burger is hot, juicy, and messy.