Preheat Oven to 350º F
1. In medium bowl, whisk salt and egg whites until foamy. Gradually add in brown sugar and vanilla.
2. In small bowl, combine flour and baking powder, and set aside.
3. In another small bowl, combine egg yolks and softened butter until it forms a paste.
4. Slowly add in flour mixture to egg white mixture, and mix until fully combined.
5. Add in the egg yolk mixture, and mix until completely blended.
6. Fold the almonds in to the entire mix with a rubber scraper.
8. Lightly grease and flour an 8x8 in. pan, and spread mixture inside.
9. Bake for 20-25 min. until toothpick comes out clean (If crumbs come out on the toothpick it is most likely the ground up almonds- look for liquidy batter, not crumbs), or until golden brown and set.
10. Cool for 10-15 min, top with powdered sugar, and then slice and enjoy!