Sauté the Vegetables: In a small skillet over medium heat, warm olive oil. Add onions and green bell pepper, sautéing for about 5-7 minutes until softened. Remove from heat to cool.

Prepare the Chicken Mixture: In a large bowl, combine ground chicken, cooled vegetables, beaten egg, crumbled blue cheese, and buffalo seasoning. Season with salt and pepper. Mix until just combined.

Shape the Patties: Divide the mixture into four portions, shaping each into patties about ½ inch thick. Place on parchment paper and refrigerate for about 1 hour.

Preheat the Grill: Preheat your grill to high heat (450-500°F) about 15 minutes before cooking. Prepare heavy-duty foil with nonstick spray and pierce holes for cooking.

Grill the Burgers: Transfer patties to the prepared foil. Grill for about 4 minutes then flip and cook for another 4-6 minutes until cooked through (internal temp 160°F).

Rest Before Serving: Remove burgers from grill and let rest on the foil for 5-10 minutes before serving.