Preheat the oven to 150°C/300°F.
Butter and lightly dust the ramekins with sugar.
Combine all the dry ingredients. set aside.
Whisk the egg-whites till they form a soft peak. Set aside.
In another bowl, combine the egg yolks, buttermilk, lemon juice and zest.
Stir in the dry ingredients in three additions, whisking gently to incorporate them each time.
Finally, fold in the egg whites carefully.
Pour into the prepared ramekins.
Place in a large water bath filled with water till about halfway and cover with foil.
Bake at 150°C/300°F for about 25 minutes.
Remove foil and continue baking for 15 more minutes.
Let cool completely, completely before turning them out of the ramekins. (Slide a thin knife around the sides to help loosen them up)
Serve with a side of ice cream or topped with these gorgeous candied lemon slices.