Combine dry ingredients except for the 4 tbsp. erythritol. Set aside.

Combine egg yolks and 4 tbsp. Erythritol cream it using a hand-mixer till pale yellow in color.

Add melted butter, lemon juice, almond milk, lemon zest and vanilla. Mix it well.

Add all dry ingredients, mix it well. Set aside. Pre-heat oven to 180C.

Using a whisk attachment, whisk the egg whites till frothy. Gradually add 1/4 cup erythritol and continue to whisk till soft peak stage.

Fold-in the egg whites in cake mixture. Do not overmix it.

Transfer the mixture in a greased 8 x 8 baking pan and bake for 40 to 45 minutes.