Adjust the oven rack to the middle position, pre-heat the oven to 375ºF (190ºC) and line a 9x5-inch (23x13cm) loaf tin with parchment/baking paper.

Add the sugar and lemon zest to a large bowl, and use your fingertips to rub the zest into the sugar. Tip: This helps to release more essential oils from the zest, and it will make your cake even more lemony and aromatic.

Add the melted butter, yoghurt, eggs and vanilla, and mix well until combined.

In a separate bowl, whisk together the gluten free flour blend, baking powder, baking soda, xanthan gum and salt.

Add the dry ingredients and the blueberries to the wet ingredients, and use a rubber spatula or a wooden spoon to mix everything together into a fairly thick batter. Make sure that there are no flour clumps.

Allow the batter to rest at room temperature for 3-4 minutes. Tip: This gives the gluten free flour blend time to absorb the moisture from the eggs and yoghurt, further thickening the batter. And the thicker the batter, the less likely the blueberries are to sink to the bottom of the cake during baking.

Transfer the batter into the prepared loaf tin and smooth out the top.

Optional extra step: Cut cold butter (straight from the fridge) into very thin strips (about 1-2mm or less than ⅛ inch thin) and arrange them in a line on top of the batter, along the middle (see blog post for photos).This creates a natural weak spot on top of the cake and thus controls where the cake will crack during baking – and it guarantees a perfect split along the centre every single time.

Bake at 375ºF (190ºC) for about 1 hour or until the cake is well risen, golden brown on top and an inserted toothpick or cake tester comes out clean. The loaf should have a large crack running along the centre.If the cake starts browning too quickly or too much, cover it with a sheet of aluminium foil (shiny side up) and continue baking until done.

Allow to cool in the loaf tin for about 10-15 minutes, then transfer the cake out of the tin and onto a wire rack to cool completely. Slice and serve.

The gluten free blueberry loaf cake keeps well in a closed container in a cool dry place for about 3-4 days.