Preheat the oven to 375° F.
Separate the eggs. Add the salt to the whites and beat the whites until light and frothy.
While beating the whites add ½ cup powdered sugar to the whites a little at a time, beat until firm, as if making meringue.**
Add the remaining powdered sugar and cocoa powder, stir until combined.
Stir in the vanilla, beer, and egg yolks until well combined.
Line a baking sheet with parchment paper. Use a cookie scoop to mound cookies onto the parchment.
Bake for 14 minutes. Pull the parchment onto the counter to allow the cookies to cool.
Spread the filling between two cookies. Refrigerate until ready to serve.