Preheat oven to 350 degrees F. Line a baking sheet with parchment paper.
In a large mixing bowl whip 4 egg yolks with 1 cup erythritol and 1 teaspoon vanilla extract until yolks become a pale yellow in color. Set aside.
4 egg yolks, 1 cup erythritol, 1 teaspoon vanilla extract
In another bowl whip 4 egg whites and 1 teaspoon baking powder until stiff peaks form.
4 egg whites, 1 teaspoon baking powder
Fold together yolks, whites, 1¼ cup almond flour, and 4 ounces unsalted butter.
1¼ cup almond flour, 4 ounces unsalted butter
Spread evenly over the lined baking tray. Bake for 10 to 12 minutes and let cool.