Beat egg whites and cream of tartar until frothy, add 2 tbsp sweetener, and whip to stiff peaks.

Beat yolks, cream cheese, remaining sweetener, vanilla, and salt until smooth.

Fold a third of the whites into the yolk mix, then gently fold in the rest. Add blueberries last and fold just until distributed.

Pour batter into a parchment‑lined 8×4‑inch loaf pan and bake at 300°F for 30–35 minutes until golden and a toothpick comes out clean. Cool in pan 10 minutes, then remove.

Slice with a serrated knife and serve warm or at room temperature.