Preheat the oven to 350°F (175°C). Line a loaf pan with parchment paper or lightly grease it to prevent sticking.
In a large mixing bowl, combine almond flour, sweetener, and baking powder. Whisk together until evenly distributed, creating a light, dry mixture.
2 cups almond flour, 1 cup granulated erythritol or sweetener of choice, 1/2 teaspoon baking powder
Add eggs, melted butter, and vanilla extract to the dry mixture. Use an electric mixer or whisk to blend until the batter is smooth and homogeneous, with no lumps, and has a slightly thickened, glossy appearance.
4 large eggs, 1/2 cup unsalted butter, 1 teaspoon vanilla extract
Pour the batter into the prepared loaf pan, spreading it evenly with a spatula. Tap the pan gently on the countertop to remove any air bubbles and level the surface.
Bake in the preheated oven for 40-45 minutes. The cake is done when the top is golden brown and a toothpick inserted into the center comes out clean. You will see slight cracks on the surface indicating proper doneness.
Remove the cake from the oven and allow it to cool in the pan for 10 minutes. Then transfer to a wire rack and cool completely before slicing to maintain its dense, moist texture and clean appearance.