Preheat oven to 350F. Prepare a 9" x 13" baking dish with foil, allowing some overhang to lift bars out when done. Cut butter into flour and powdered sugar, and press mixture into baking dish. Bake 18-20 minutes or until light brown. Set on a wire rack to cool. Spread out 1 cup coconut, for topping, on a baking sheet and bake in 350F oven for 3-6 minutes, stirring every minute or so until coconut is golden brown. Let cool. Make filling: Combine cream, milk, eggs, sugar, cornstarch and salt in a large saucepan and bring to a boil over medium-low heat, whisking constantly until it's thick and bubbling. Add extracts and the 1 1/2 cups of coconut and stir. Pour filling over cooled crust, letting it cool for a bit on the counter before placing in the fridge to chill 2-4 hrs.
Make topping: Put water in a small bowl and sprinkle evenly with gelatin. Let set for 2 minutes before microwaving it for 30 seconds and whisking to dissolve the gelatin. Using a chilled bowl and beaters, whisk the 2 cups of whipping cream and powdered sugar together until the cream forms stiff peaks, stopping to add gelatin mixture about halfway through. Dollop the cream over your bars and gently spread it around. Top with toasted coconut. Chill until ready to serve, to let the whipped cream set up. Use the overhanging foil to lift bars out of the dish and slice with a sharp knife.