Preheat the oven to 180C/350F degrees.
Line an 8 inch spring form cake tin with parchment paper.
In a large bowl whisk the butter and sweetener together until smooth.
Whisk in the eggs one at time.
Add the sour cream and vanilla extract and continue to whisk.
Add the almond flour, protein powder, ginger, all spice cinnamon, nutmeg, baking powder, baking soda and salt. Whisk until you have a smooth cake batter.
Gently stir in the cranberries and walnuts.
Pour the cake mixture into the cake tin and bake for 45-50 minutes until the top is golden and the cake is firm. Check the cake is cooked through with a toothpick.
Allow to cool in the tin for 10 minutes before removing the cake.
Slice and enjoy!