Combine the flour + salt and baking powder. Reserve
First, you need to boil the lemon. Why is that? Boiling the lemon obviously softens them but most importantly, they remove most of their bitterness.
Heat a pot with water and bring it to a boil. Add the lemons in and let them simmer for 30-40 mins. Remove them from the pot and let them cool completely before proceeding, you don’t want to burn your fingers. Note that you can do this step a day in advance.
Now to remove the seed, Over a mixing bowl, I tear a lemon with my finger and break it apart. I then remove all the seeds and the piece at the center of the lemon. repeat for each lemon. Toss the lemons in a food processor and blend them.
Split the eggs into a separate bowl, make sure that you use a large mixing bowl for the eggs yolks as you will combine all ingredients into it. Dump the sugar and maple syrup in the yolks and whisk. Finally, dump the dry ingredients and lemon puree in the yolks and mix everything together.
Put the egg whites in a stand mixer bowl and whisk until you get soft peaks. Then slowly fold it in the puree.
Pour the mixture into a nonstick pan. If you have a springform pan these are perfect for this task. I found one at my best pals at Walmart for 6.99$. I would recommend you grease it up with butter and a light coat of flour just to make extra sure it doesn’t stick.
Bake at 350F for 50 minutes, top needs to be well browned.
Let cool about an hour before cutting. You can dust a light coat of icing sugar on top.