Pre heat the oven to 160 degrees and line the bottom of a 9 inch square tin with baking parchment.
In a bowl, mix the egg yolks and 1 whole egg with the granulated sweetener, spices and cooked pumpkin (or butternut squash).
Fold in the flour, xanthan gum and baking powder.
In a separate bowl, whisk the egg whites until stiff. Fold these in carefully so as not to knock out too much air, but ensure they are fully incorporated or there will be white patches of egg white in the cooked cake.
Bake for 35-40 minutes until golden brown.
Once cooked, turn out upside down onto a wire rack and leave to cool before taking off the parchment.
Cut into 12 pieces. Serve warmed as a dessert or cold as a cake - this can be dusted very lightly with Sukrin Icing Sugar immediately before serving to make it look irresistible!