For the Cake:

1. PREP: Center a rack in the oven and preheat the oven to 350 degrees F. Grease two 9 x 2 inch round cake pans with baking spray or butter. Then line the bottom of each pan with a round of parchment or wax paper and grease again. Put the pans on a baking sheet and set them aside.
2. SIFT TOGETHER DRY INGREDIENTS: In a medium bowl, sift together the flour, baking powder, and salt.
3. WHISK BUTTERMILK & EGG WHITES: In another medium-sized bowl, whisk together the milk and egg whites.
4. ADD LEMON ZEST TO SUGAR: Put the sugar and lemon zest in the bowl of a stand mixer (or another bowl) and rub the mixture together using your fingers until the sugar is moist and fragrant.
5. CREAM BUTTER AND SUGAR: Add the butter to the sugar mixture and beat with a paddle or whisk attachment, or with a hand mixer, at medium speed until the butter and sugar are very light and fluffy, about 3 minutes.
6. MIX INGREDIENTS: Start by mixing in the lemon extract, and then add one-third of the flour mixture, keeping the mixer on medium speed. Next, add half of the milk-egg mixture, then add half of the remaining dry ingredients. Mix until incorporated. Then add the rest of the milk and eggs, beating until thoroughly combined. And finally, add the last of the dry ingredients. Beat the batter at medium speed for an additional 2 minutes to ensure that it is thoroughly mixed and well aerated.
7. BAKE: Divide the batter between the two pans and smooth the tops with a rubber spatula or the back of a spoon. And bake for 30-35 minutes, or until the cakes are well risen and springy to the touch – a thin knife inserted into the centers should come out clean. 
8. COOL: Transfer the cakes to cooling racks and cool for about 5 minutes, then run a knife around the sides of the cakes, and remove the cakes from the pan and peel off the paper liners. Cool to room temperature, right side up, on a metal cooking rack. Make sure the cake is cooled completely before frosting.
9. The cooled cake layers can also be wrapped airtight and stored at room temperature overnight or frozen for up to two months.

For the Lemon Buttercream:

1. BEAT THE BUTTER: Using a handheld or stand mixer fitted with a paddle attachment, beat the butter on medium speed until creamy, about 2 minutes.
2. ADD THE SUGAR, LEMON JUICE + VANILLA: Add 4 cups of confectioners’ sugar, lemon juice, and vanilla extract. Continue beating on low speed for 30 seconds, then increase to medium-high speed and beat for 2 minutes.
3. ADJUST TEXTURE: Add up to 1/2 to 1 cup more confectioners’ sugar if frosting is too thin and add a pinch of salt if frosting is too sweet. If the frosting is too thick, you can add a tablespoon or two of cream.
4. STORAGE: This frosting can be made ahead of time and stored for up to 1 week in the refrigerator or up to 3 months in the freezer. If freezing, you can thaw in the refrigerator and then beat the frosting on medium speed for a few seconds, so it’s creamy again. 

To Assemble:

1. CUT LAYERS IN HALF: Using a sharp serrated knife and a gentle sawing motion, slice each layer horizontally in half.
2. ADD JAM: Put one layer cut side up on a cardboard cake round or a cake plate protected by strips of wax or parchment paper. Spread it with one-third of the preserves.
3. ADD BUTTERCREAM: Cover the jam evenly with about one-quarter of the buttercream.
4. REPEAT: Top with another layer, spread with preserves and buttercream, and then do the same with a third layer (you’ll have used all the jam and have buttercream leftover). Place the last layer cut side down on top of the cake and use the remaining buttercream to frost the sides and top.
5. ADD THE COCONUT: Press the coconut into the frosting, patting it gently all over the sides and top.

For Storing:

• LEFT-OVERS: The cake is best the day it is made, but you can refrigerate it, well covered, for up to two days. Bring it to room temperature before serving.
• FREEZE: If you want to freeze the cake, slide it into the freezer to set, then wrap it really well – it will keep for up to 2 months in the freezer; defrost it, still wrapped overnight in the refrigerator.