Preheat oven to 400°F. Line one (or two, if necessary) baking sheets with parchment paper and set aside. In a medium-sized bowl, stir together the drained crushed pineapple and coconut flakes and set aside.
Roll out one sheet of puff pastry into a roughly 12"-square onto a lightly floured surface, taking care to flour rolling pin as well to prevent sticking. You may want to refrigerate the remaining puff pastry sheet while you prepare the first one to make sure it doesn't become too warm.
On one diagonal half of each pastry square, place approximately 3 tbsp of the pineapple and coconut mixture and situate it into a triangle shape, leaving a 1/2" border along either side.
Dip your finger in water and run it along the edges of each puff pastry square. Fold the diagonal half of each puff pastry square over top of the filling and press along the edges to adhere.
Press the tines of a fork along the edges to help them stick.
Repeat process with the second sheet of pastry dough. Now you will have eight turnovers.
Brush tops of each turnover with milk.
Bake for 18-20 minutes, or until turnovers have darkened to a golden brown on the tops and the edges and the dough has cooked through.
Transfer turnovers to a wire rack to cool to your preferred temperature. Turnovers can be served warm or room temperature, with warm caramel sauce drizzled over top for an extra treat!
Nutritional info includes 1 teaspoon of caramel sauce per turnover. The turnovers are fairly large, so you may wish to cut them (and the nutritional info) in half for serving.