Preheat the oven to 350°F (175°C) and line a loaf pan with parchment paper.

Separate the eggs, placing the whites in one bowl and the yolks in another.

Using a hand mixer, whip the egg whites with the cream of tartar until stiff peaks form.

In a separate bowl, mix together the egg yolks, cream cheese, melted butter, psyllium husk, baking powder, and salt until smooth. Let the mixture rest for a couple of minutes so the psyllium can thicken.

Add one-third of the whipped egg whites to the yolk mixture and fold to lighten it. Gently fold in the remaining whites until the batter is combined without overmixing.

Transfer the batter to the prepared loaf pan, smoothing the top. Bake for 50 to 60 minutes, or until a toothpick inserted in the center comes out clean.

Allow the loaf to cool completely before slicing. The texture improves and sets as it cools.