Make shortbread crust: Preheat your oven to 350°F. Prepare a 9 x 13 in. baking dish with a foil sling (I use one long sheet across the length of my dish, and two overlapping short sheets across the width of my dish — just arrange it so that it has some overlap and overhang to help you pull the bars out after they’re finished). Cut the butter into the flour and powdered sugar and press into the baking dish (I used a food processor to cut the fat into the flour — about 6-10 pulses — and then the bottom of a glass to press the mixture into the pan). Bake 18-20 minutes or until light brown. Set on a wire rack.Toast coconut for the topping: Spread about 1 cup of the coconut flakes out on a baking sheet and bake in the oven along with your shortbread crust for 3-6 minutes, stirring every minute or so, until the coconut is golden brown. Spread it out on a plate to cool completely.Make coconut cream filling: Combine the half-and-half, coconut milk, eggs, sugar, cornstarch, and salt in a large saucepan and bring it to a boil over medium-low heat, whisking constantly until it’s thick and bubbling (this can take anywhere from 15-30 minutes. Just do it. It’s worth it.) Add coconut and vanilla extracts and the 1 1/2 cups of untoasted coconut and stir. Pour this filling over your cooled crust, letting it cool for a bit on the counter before sticking the whole thing in the fridge to chill until firm, about 2 to 4 hours.Make whipped cream topping: Put 1 tablespoon cold water in a small bowl and sprinkle the gelatin evenly over the top. Let it soften for 2 minutes before microwaving it for 30 seconds and whisking to dissolve the gelatin. Using a chilled bowl and beater, whisk the 2 cups of heavy 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. Sprinkle on toasted coconut. Chill until ready to serve to let the whipped cream set up. Use the sling to pull the bars out of the dish, slice with a sharp knife, and enjoy!