Ensure the eggs are at room temperature. (If I forget to take them out beforehand, I just dip them in warm water for a few minutes to take the chill off.)
Measure out your blueberries in a cup and leave them to defrost a little if using frozen.
Pull out your muffin tin and greaseproof baking paper. Cut 8 squares of paper (about 10cm x 10cm - about 4 x 4inches.) I also grease these with butter as these are delicate muffins that stick to everything. My first few attempts rammed this home to me!
Separate the eggs.
With an electric beater, whip the whites and salt until little peaks form. (About 3 minutes.)
In a bowl mix the egg yolks, sugar, bicarb soda.
Sift the flour over the egg whites and mix together carefully.
Then mix through the yolk mixture. (Try to mix the least you can but still have it combine because otherwise you squash all the air in the egg whites.)
Line each muffin section with paper then fill two tablespoons full of the mixture, keep doing this until all 8 are in the tin. Then top up each evenly by the tablespoon until all the mix is used.
Then drop a few blueberries in each and keep going until all the blueberries are used up. They will sink to the bottom while cooking but I found if I mix them with the mixture it squashes the egg whites more and makes the whole thing purple!
Bake at 180C (360F) for 15 minutes until just brown on top. Allow to cool for a few minutes before eating.
Store extras in an air tight container in the pantry overnight. Now I’m not sure how much longer they last than a day because we make this small batch eat some and then warm them up in the microwave and have them the second day. So if you keep them longer than this and they are still ok please let me know.