Slice tomato and cut onion into rings of ½ inch.
In large mixing bowl, combine ground chicken, egg (lightly beaten), garlic powder, onion powder, smoked paprika, and parsley. Mix together with clean hands.
Scoop a hand full of mix and shape into a ball with hands. Toss mix in between hands to form patty. Place patty on a piece of parchment paper. Use 3 fingers to press down on the center of the patty to gently create a shallow crater.
Sprinkle half of seasoned salt and black pepper on only the top of patties. Heat grill or skillet to 350°F.
Melt butter on grill or skillet and begin to place patties with the seasoned side down. Sprinkle remaining seasoning on the now-upside of patties. Let cook for 5-7 minutes to allow bottom half to turn white. Then flip patties and let cook for another 5-7 minutes.
Sit buns on grill or skillet to toast. While toasting, mix together mayonnaise, garlic, and truffle in a small bowl.
Remove burgers from heat to cool for 3 minutes then place on buns. Top burger with tomato, onions, and arugula. Spread generous amount of truffle mayonnaise on top bun and enjoy!
