Preheat the oven to 190 °C. Place the puff pastry slices on a baking tray lined with baking paper. Leave to thaw.
Cut the cheeks off the mangoes on either side of the stone. Slice the halves into strips from top to bottom and from left to right all the way up to the skin. Turn the skin inside out and cut the cubes off. Place the mango cubes in a mixing bowl.
Mix the mango with the cane sugar, honey and granola. Squeeze the lime and add the juice. Coarsely chop the cashew nuts and add.
Spread 2 tablespoons of mango mixture in the center of each slice of puff pastry. Make sure to keep an edge of 1 cm free.
Beat the egg. Fold the puff pastry edge a bit over the mango mixture to create a nice round shape. Brush the folded edges with egg. Bake the galettes in approx. 25 minutes in the middle of the oven until golden brown.
