Preheat the oven to 350°F (177°C). Grease a loaf pan with butter or cooking spray and set aside.
In a large mixing bowl, combine almond flour, erythritol, baking powder, and salt. Whisk until evenly mixed, creating a uniform dry mixture with no lumps visible.
1 1/2 cups almond flour, 1/2 cup erythritol or other keto sweetener, 1/2 tsp baking powder, 1/4 tsp salt
In a separate bowl, beat the eggs until slightly frothy. Mix in the melted butter and vanilla extract, whisking until well combined and slightly thickened.
4 large eggs, 1/2 cup unsalted butter, 1 tsp vanilla extract
Pour the wet mixture into the dry ingredients. Using a spatula or spoon, fold gently until the batter is smooth and homogeneous, with no streaks of flour remaining.
Transfer the batter into the prepared loaf pan, smoothing the top with a spatula. Place the pan on the middle rack of the oven.
Bake for 45 minutes, or until the top is golden brown and a toothpick inserted in the center comes out clean. Once baked, remove from oven and let cool in the pan for 10 minutes before transferring to a wire rack to cool completely.
