Preheat the griddle. Turn all burners to medium-high and heat the Blackstone for a full 10 minutes until the surface reaches 375–400°F.
Oil the surface. Drizzle 1 tablespoon of oil onto the griddle and spread it with a spatula. Do not oil the patties.
Place the patties. Set the frozen patties directly on the oiled surface, spacing them at least 1 inch apart. Do not press or move them.
Dome for 5 minutes. Cover the patties with a basting dome and cook undisturbed for 5 minutes. The trapped steam thaws the centers while the bottoms sear.
Season and flip. Remove the dome. Season the seared side with salt, pepper, and Montreal seasoning. Flip once.
Finish cooking. Cook uncovered for another 4–5 minutes, until the patties reach an internal temperature of 160°F for beef (165°F for turkey or chicken).
Add cheese (optional). During the last minute, top each patty with a slice of cheese and re-cover with the dome to melt.
Toast the buns. Slide the buns cut-side down onto the griddle for the final 30–60 seconds.
Build and serve. Stack each burger with your toppings and serve immediately.