Preheat oven to 325 degrees. Line the bottom of a 9-inch springform pan with parchment paper and then coat with cooking spray.
Combine eggs, turbinado sugar and salt in the top of a double boiler, set aside until water boils. Fill the bottom of your double boiler 1/4 full with water and bring to simmer. Set over boiling water, whisking until smooth and all sugar has dissolved.
Remove and place into the bowl of a stand mixer fitted with a whisk attachment or in a large mixing bowl. Whisk at a medium speed until mixture has doubled in size. If you have a stand mixer, set it for 5 minutes.
Meanwhile combine 12 ounces bittersweet chocolate in the double boiler over low heat. Stir until melted.
Add beer and vanilla to egg and sugar batter, followed by melted chocolate. Continue to whisk at medium speed.
Lastly, add room temperature butter until fully incorporated and smooth.
Pour into prepared springform pan. Bake for 30-35 minutes or until the cake passes the toothpick test.
Allow cake to cool while still in springform pan for approximately 15 minutes while you make the meringue. Raise oven temperture to 400 degrees.
In medium bowl, beat egg whites and cream of tartar with electric mixer on high speed until foamy. Beat in sugar, 1 tablespoon at a time; continue beating until stiff and glossy. Do not underbeat. Beat in vanilla.
Using a large spoon, frost cake making big "wisps". Bake for an additional 10-12 minutes or until peaks start to crisp and brown.
Remove from oven and carefully release from springform pan to your serving platter. Cake might weep, but this is normal. It is best consumed the same day.