Preheat oven to 350 degrees F (177 degrees C). Brush sides and bottom of a 8 or 9 inch cake pan with coconut or olive oil. Cut a circle of parchment paper to fit the bottom of the cake pan, place in pan, brush with oil, set aside.
In a medium bowl, beat egg whites until stiff peaks form, set aside. In a small bowl whisk egg yolks, yogurt, stevia, alcohol free vanilla and lemon zest, set aside.
In a large bowl, add almond flour, then add egg whites and egg yolk mixture, fold gently to combine. Pour the cake mixture into prepared pan and bake for 20 to 25 minutes, until top of cake springs back when pressed and a toothpick inserted in center of cake comes out clean.
Cool in pan 10 minutes. Run a knife around the edge of the pan to loosen cake. Invert cake to remove from pan and remove parchment paper. Reinvert cake and transfer to a wire rack to cool completely. Using a serrated knife, slice and serve with a spoonful of Lemon Curd.
THE LEMON CURD:
In a medium sauce pan off heat, whisk together eggs, stevia, alcohol free vanilla and lemon zest. Add melted coconut oil, and whisk to combine. Finally, whisk in lemon juice.
Now place pan over medium heat, whisking constantly, until mixture becomes opaque and just begins to thicken, 1 to 2 minutes. Remove pan from heat and pour curd through a mesh strainer into a bowl.
Cool and serve. The lemon curd can be refrigerated in covered container for 3 to 4 days.