Add coconut flakes to a large nonstick skillet and saute over medium-high heat for 3-4 minutes until edges begin to brown. Transfer to a bowl or plate and set aside.
Add butter to the pan and stir until melted. Add brown sugar and cinnamon and stir until dissolved and mixture is thick and saucy.
Place pineapple rings in the skillet in a single layer so they aren't overlapping. Cook 2-4 minutes on each side until hot throughout and very tender.
Remove from heat and top each pineapple ring with a scoop of vanilla ice cream. Spoon some of the pan sauce over the ice cream and sprinkle with coconut flakes and chopped macadamia nuts. Serve immediately.
You can used canned pineapple rings in a pinch but I highly recommend using fresh if you can get your hands on some!