Line a baking sheet with foil and grease with cooking spray. Lay pineapple rings on the baking sheet in an even layer.
Season both sides of the salmon with salt and pepper and place fillet on top of pineapple rings.
In a small microwave safe bowl, melt butter. Add minced garlic, cilantro, ground ginger, sesame oil and red pepper flakes. Brush all over salmon fillet.
Bake until the salmon is cooked through approximately 25 minutes. Switch oven to broil and broil for 2 minutes or until top is ideally charred.
Garnish with sesame seed and scallions, and squeeze lime over top before serving.