Beat the egg white with salt until you can cut into it with a knife. Preheat the oven to 160 ° C (convection).
Use a whisk to fold the powdered sugar, vanilla extract and lime zest evenly into the beaten egg white. Finally, carefully fold in the coconut flakes, chocolate chunks and the dried raspberry pieces with a silicone spatula until an even, fluffy dough is formed.
Line a baking sheet with baking paper, brush with the melted butter and spread the dough over an area of approx. 30 x 30 cm. Bake in the preheated oven for 15 minutes.
Take out, pull down from the baking sheet with the baking paper and place fresh baking paper on the baking sheet.
Cut the cake in 5 x 4 rows, making 20 pieces. Carefully remove each piece with a spatula and place it upside down on the fresh baking paper. Leave some space between the pieces. Bake for another 8-10 minutes, take out of the oven and let cool down.
Super suitable for coffee, tea, as a snack in between, or also for the school sandwich box!