Thaw the puff pastry dough. Cut it into long, skinny strips.
Lay out the dough strips on a baking sheet lined with parchment paper. Bake them at 350°F for about 15 minutes or until golden brown.
With a stand mixer or hand mixer, combine the dulce de leche with softened butter until you get a smooth, creamy texture.
Line a rectangular plate or cutting board with plastic wrap. Spread a bit of cream on it and start stacking the baked puff pastry dough strips, applying a generous amount of dulce de leche cream between each layer. Next, wrap the entire cake in plastic wrap and let it sit overnight.
Remove the wrap from the cake, cut off the jagged cake ends. Sprinkle the top of the cake with coconut flakes. Keep the cake refrigerated until you plan to serve it.