Preheat oven to 300 degrees. Draw three 8-inch circles on two pieces of parchment paper (2 on one piece, one on another) and place them, drawn-side down on two baking sheets.
Separate 3 of the eggs. Beat the egg whites on medium speed in a mixer until foamy. Add the salt and cream of tartar and raise the speed to high. Gradually add ¾ cup of sugar while the egg whites are beating. Beat in the vanilla then fold in the almond meal. Divide the meringue evenly into the three circle and spread evenly. Bake for 45 minutes or until lightly golden. Let cool completely.
Finely zest two of the lemons and squeeze enough juice to equal ½ cup.
Place the egg yolks and whole egg in a medium saucepan and whisk in ¾ cup of sugar. Add the lemon zest and juice and whisk well. Place over medium heat. Switch to s wooden spoons and cook, stirring constantly, until the mixture thickens and coats the back of the spoon, about 6 minutes. Add the butter, one piece at a time, and stir until fully incorporated before adding the next. When done, strain into a bowl. Place a piece of plastic wrap directly on the surface and refrigerate until cold, about 1 hour.
When ready to assemble, whip the cream with the powdered sugar until stiff peaks form. Stir about 1/3 of the whipped cream into the lemon curd then fold in the rest.
Place one meringue layer on a cake plate, top with one third of the lemon mixture then repeat the layers ending with the lemon. Sprinkle some sliced almonds on top and serve.