This is one of my most favorite homemade cakes.  I found it on Martha Stewart’s website after watching her tv show one day and drooling :O).  I added the link to her site on the picture above if you want to see the official recipe. 

NOTE:  The only thing I have changed when I make the cake is I sometimes add coconut to the outside by taking about 1/4 cup milk, adding lemon extract (or lemon juice) and a few drops of yellow food coloring, then I soak a bag full of coconut (or use  freshly grated…yum!) in the mixture for a few minutes and mix it up until well-coated.  This turns the coconut yellow.  It is also a good way to freshen coconut if it is a little dry.  I then put the coconut all over the finished iced cake as the very last step.

Cake Recipe

Makes two 9-inch cakes
3 cups cake flour (not self-rising)
2 teaspoons baking powder
1 teaspoon salt
1 1/2 cups (3 sticks) unsalted butter, room temperature
2 1/4 cups sugar
1/2 teaspoon pure vanilla extract
1 cup milk
8 large egg whites
Seven-Minute Frosting (recipe to follow)
1 cup Lemon Curd (recipe to follow)
Directions
1.Preheat oven to 350 degrees. Butter two 9-by-2-inch round cake pans; line bottoms with parchment paper rounds. Butter parchment, and dust with flour, tapping out excess; set aside.
2.Into a medium bowl, sift together flour, baking powder, and salt; set aside. In the bowl of an electric mixer fitted with the paddle attachment, beat butter and 2 cups sugar until light and fluffy, 3 to 4 minutes, scraping down sides of bowl as needed. Beat in vanilla. With mixer on low speed, add flour mixture in three parts, alternating with milk and beginning and ending with flour; beat until just combined. Transfer mixture to a large bowl; set aside.
3.In the clean bowl of an electric mixer fitted with the whisk attachment, beat egg whites on low speed until foamy. With mixer running, gradually add remaining 1/4 cup sugar; beat on high speed until stiff, glossy peaks form, about 4 minutes. Do not overbeat. Gently fold a third of the egg-white mixture into the butter-flour mixture until combined. Gently fold in remaining whites.
4.Divide batter evenly between prepared pans, smoothing with an offset spatula. Bake, rotating pans halfway through, until cakes are golden brown and a cake tester inserted in centers comes out clean, 30 to 35 minutes. Transfer pans to a wire rack to cool 20 minutes. Invert cakes onto rack; peel off parchment. Reinvert cakes, and let them cool completely, top sides up.
5.Using a serrated knife, trim tops of cake layers to make level. Place one layer on a serving plate, cut side up. Using a pastry bag fitted with a coupler, pipe frosting around the perimeter. This dam will prevent the lemon curd filling from seeping out. Fill cake with lemon curd. Place other cake layer on top, cut side down. Spread entire cake with frosting, swirling to cover.
From The Martha Stewart Show, April 2006

Seven Minute Frosting

Makes about 8 cups
1 1/2 cups sugar
2 tablespoons light corn syrup
6 large egg whites
1 teaspoon pure vanilla extract
Directions
1.In the heatproof bowl of an electric mixer set over a saucepan of simmering water, combine sugar, corn syrup, 1/4 cup water, and egg whites. Cook over medium heat, stirring frequently, until mixture registers 160 degrees on an instant-read thermometer, about 2 minutes.
2.Attach bowl to a mixer fitted with the whisk attachment. Beat mixture on high speed until glossy and voluminous, about 5 minutes. Beat in vanilla. Use immediately.

From The Martha Stewart Show, April 2006

Lemon Curd

Makes 1 1/2 cups

• 6 large egg yolks
• Zest of 2 lemons
• 1/2 cup freshly squeezed lemon juice (about 4 lemons)
• 12 tablespoons sugar
• 1/2 cup (1 stick) unsalted butter, cold, cut into pieces

Directions

1. Prepare an ice bath fitted with a medium bowl; set aside. Whisk together yolks, zest, juice, and sugar in a small saucepan. Set over medium heat, and stir constantly with a wooden spoon. Cook until mixture is thick enough to coat the back of the wooden spoon, 5 to 7 minutes.
2. Remove pan from heat. Add butter, 1 piece at a time, stirring until incorporated. Pass through a fine mesh sieve into prepared medium bowl. Stirring frequently, let stand until cool.
3. Place a sheet of plastic wrap directly on surface of curd to prevent skin from forming; wrap tightly. Refrigerate until firm and chilled, at least 1 hour. Store refrigerated in an airtight container for up to 2 days.