Preheat oven to 300 degrees F. Line two baking sheets with silicone baking mats or parchment paper.
Whisk the egg white in a bowl until frothy. Add the sugar and whisk until incorporated. Add the almonds and raisins to the bowl and stir everything together making sure all of the almonds and raisins are coated with the egg mixture.
Spoon clusters of the mixture (about 1 ½ tablespoons each) onto the prepared baking sheets. Form them into small mounds with your hands. The clusters won’t stick together but they will once they’re baked.
Bake in the oven, one tray at a time, 18-20 minutes until set. Remove from oven and let the clusters cool completely on the baking sheets. When they’re completely cool, carefully lift the clusters from the baking sheets with a spatula.
Melt the chocolate in a bowl in the microwave or in a double boiler. Using an offset spatula or butter knife, spread a thin layer of chocolate over the bottom of each cluster. Lay each cluster down on a plate (chocolate side up) and refrigerate until chocolate is firm. Flip the clusters right side up before serving.