Preheat your oven to 300°F. Set up a double boiler to melt your baker’s chocolate and butter together. If you don’t have a double boiler set up, just use a pan on low heat.
Once the chocolate and butter are melted and combined, add in half a cup of erythritol and stir until dissolved. This may take a while so be patient and keep the flame low!
Once that’s ready, set it aside while your prepare your eggs. Separate 3 eggs and beat the egg whites until they’re foamy. Slowly add 1/4 cup of erythritol while beating the egg whites. They should turn glossy and form stiff peaks.
Clean off your beaters and beat your 3 egg yolks with the last 1/4 cup of erythritol. They should double in volume and turn a pale yellow.
Add your buttery chocolate mixture to these pale yellow egg yolks and stir to combine.
Add in 1/2 cup of cocoa powder and combine. Add the vanilla and salt in this step as well.
Now add a third of your egg whites at a time and fold them in gently. Repeat until all the egg whites are evenly distrubited. Do not over combine or you may deflate the egg whites too much.
Spray a spring form pan with cooking oil and pour your chocolate cake batter in. We laid our pan on a sheet of aluminum foil to catch any stray oil that seeps out. Bake for 35 minutes.