Preheat the oven to 180°C/350°F degrees. Line the 9x9 inch baking pan with parchment paper.
In a large mixing bowl whisk all dry ingredients.
In a separate bowl mix together wet ingredients. Pour the wet ingredients into the dry ingredients and mix with spatula until completely combined.
Stir in freshly cut apple.
Transfer the batter to the baking pan. Use spatula to spread the batter evenly in the pan.
Bake for 45-50 minutes or until golden brown.
Allow the cake to cool for at least 30 minutes before cutting and serving. Serve warm dusted with powdered erythritol or a scoop of ice cream.