1. Preheat the oven to 350 and prep your baking sheet with parchment paper
2. Melt the butter in a medium sauce pan
3. Once melted, stir in the brown sugar
4. Bring to a boil over med-high heat and cook for 1 minute
5. Remove from heat and transfer into bowl
6. Whisk in the vanilla and mix in the almond flour and salt
7. Let cool for 5 minutes then whisk in egg white
8. Let the dough sit for 10 minutes to thicken (dough should be thinner)
9. Drop one TBSP of batter onto the prepared baking sheet
10. Place 3 inches apart
11. Bake for 7-9 minutes, until golden brown around the edges
12. Allow cookies to cool on a baking sheet for 5 minutes, then transfer to wire rack and allow to completely cool

To make filling: 

1. Melt chocolate in the microwave in 30 second increments, stirring each time until smooth and no chips remain
2. Sandwich the cookie with a spread of chocolate