Preheat your Blackstone griddle to medium-high heat. Once hot, add the crumbled breakfast sausage and cook until browned and fully cooked. Transfer the sausage to a plate and set aside.

Using the same griddle, sauté the diced onions and bell peppers until they soften and begin to caramelize. Push the vegetables to one side of the griddle to keep warm.

On the other side of the griddle, pour in the whisked eggs. Scramble them while seasoning with salt and pepper. When cooked through, mix the scrambled eggs with the sautéed vegetables.

Place a tortilla flat on the griddle. Sprinkle a generous handful of both cheddar and mozzarella cheese over one half of the tortilla. Top with cooked sausage, scrambled eggs, and vegetables, then fold the tortilla in half to form a quesadilla.

Lower the heat to medium and cook each quesadilla for a few minutes on each side until the outside is golden and crispy and the cheese inside is melted. Add butter or oil to the griddle as needed to achieve a crispy texture.

Remove the quesadillas from the griddle and let them rest for a minute. Cut into wedges and serve hot with salsa, sour cream, or your favorite dipping sauce.