Place the egg whites and cream of tartar into your stand mixer bowl and add the whisk attachment. Whisk until stiff peaks form.

In a separate bowl, beat the maple syrup, Swerve and coconut oil together until they’re creamy.

Gently mix in the egg yolks.

Add coconut flour, vanilla, apple cider vinegar, baking soda, salt and zest to the mixture. Beat until combined.

Fold the egg whites into the batter very gently, working in batches.

Spoon half of the batter into the loaf pan and scatter half of the blueberries on top.

Pour the remaining batter over the top and smooth the top down. Scatter the rest of the blueberries on top.

Place the streusel ingredients into a small bowl and rub the coconut oil through with your fingertips until it resembles large crumbs. Scatter over the top of the cake.

Bake for 45 minutes until cooked in the center.

Store, wrapped in cling wrap or foil, for up to five days. Cake will soften over time but can be lightly toasted to freshen. Can be sliced, wrapped and frozen.