Poppyseed Chiffon Cake: Using an electric whisk, beat egg whites and cream of tartar until it is foamy and increasing in volume. Then slowly add in 1/2 cup sugar and continue whisking for a few minutes until stiff, glossy peaks form.
In another bowl, combine the dry ingredients (flour, baking powder, salt, lemon zest, poppyseeds).
Preheat oven to 325ºF.
In a third bowl, whisk the wet ingredients (egg yolks, 1 c sugar, oil, vanilla, lemon juice) until pale yellow.
Alternatively add in 1/3 of the flour mixture and 1/3 of milk to the wet ingredients, and continue adding the batches and whisking until well incorporated.
Using a spatula, gently fold in the egg whites. This is what makes the cake light, so if in doubt, under mix.
Pour cake batter into 2 – 9″ cake pans, ungreased. Bake for 30 minutes. Then increase oven temperature to 350ºF and continue baking for about another 10 min, or until cake turns golden brown and toothpick comes out clean. To cool the cake, turn the cake and pan upside down on a cooling rack until room temperature. Then use a spatula to help release the sides and bottom of the cake from the pan.
Coconut Frosting: While the cake bakes, make the frosting. Combine the egg whites, sugar and cream of tartar on the top half of a double boiler on low heat.
Using an electric whisk, beat the egg mixture until it begins to thicken. Then add in vanilla extract and continue whisking on med-high till stiff peaks form. Remove from heat and stir in coconut. Let it cool to about room temperature before use.
Assembly: Set the first cake on the serving plate. Using a small portion of the frosting, create a crumb layer coat to seal in all the crumbs. Then frost the first layer with about 1/3 of frosting. Layer the second cake on top. Repeat the crumb layer and frosting layer. Then frost the sides of the cake till completely covered. Garnish with more toasted coconut as desired.
Notes
Cream of tartar is essential for stabilizing the whipped frosting
For a whiter frosting, only toast 1/4 c of coconut for decoration and mix in un-toasted coconut in the frosting
Double boiler method: Use 2 pots or a heat-proof bowl on top of a pot, where the lower pot has about 2-3 cups of boiling water