Preheat oven to 350°F. Grease an 8 inch round springform pan. Then line with parchment paper on sides and on bottom. You need to line with parchment paper because cake will stick even if you grease pan. Greasing it first makes the parchment paper stick better to the pan.
Beat eggs on highest speed with mixer until triple in volume, about 8 minutes. Make sure you beat the eggs long enough. This cake depends on the egg volume. Add in sugar and beat for another minute.
Measure out peanut butter into a glass bowl. Add in 1/3 of the egg mixture. Stir with a spatula in the same clockwise direction until all of the egg is mixed in and no streaks remain. Make sure you stir gently with a spatula and do not use a whisk or a mixer, as you will deflate the eggs too much. Then add another 1/3 of egg mixture and stir again until no egg streaks remain. Scrape the bottom of your bowl a few times to make sure none of the peanut butter has sunk to the bottom. Pour in remaining third and make sure to scrape the foam that sticks to the mixing bowl into the cake batter and stir until no streaks remain.
Pour batter into springform pan. Bake for 20-25 minutes until knife inserted comes out clean. Let cake cool before cutting and serving.
The nutrition information provided are only estimates based on an online nutritional calculator. This is not a comprehensive list of all the nutrients in the recipe (i.e., does not include vitamins, cholesterol, etc). I am not a certified nutritionist. Please consult a nutritionist or doctor for accurate information and any dietary restrictions and concerns you may have.