Step 1

Preheat oven to 375 degrees F. Coat an 8- x 4-inch loaf pan with cooking spray.

Step 2

In a medium bowl, with an electric mixer, beat together egg whites and cream of tartar until soft peaks form.

Step 3

In a large bowl, combine egg yolks, 1/3 beaten egg whites, butter, almond flour, baking powder, and salt; mix well.

Step 4

Add remaining 2/3 beaten egg whites and mix until thoroughly combined. Don't overmix. Pour mixture into prepared loaf pan.

Step 5

Bake 25 to 30 minutes or until a toothpick inserted in center comes out clean. Let cool 10 minutes, then remove from pan to finish cooling completely.