When I first saw the recipe from Martha Stewart's Baking Handbook, my first reaction was, "You expect me to make this???"
It's actually not too bad, just a lot of steps. The kind of thing that you might do for a special occasion. I'll break down the process, and give you some ideas for easy short cuts.
First, make some lemon curd. (I've posted my go-to stove-top recipe below.) You could also just buy some at the store, but I prefer the real thing, and it's not that hard to make in advance. And you can keep it in the fridge for 4-5 days.
Next, bake your favorite lemon cake recipe, two round 9-inch layers. You could even do this from a mix if you wanted to cheat, but here's a link to Martha's recipe, should you choose to go the official route.
When the cake layers have cooled, you can wrap them in plastic or proceed to the next step, which is to whip up some lemon buttercream frosting. Again, you could go store-bought if you want to save time.
Now have the cake layers, lemon curd, and frosting in front of you. Cover the edges of a serving plate with several strips of wax paper. Set the first layer of cake on the strips. (Be sure you can easily yank the strips out from under the cake when you're finished. The idea is to get rid of the mess you'll get from the frosting process.)
Saw the cake in half with a serrated knife. (You can stick toothpicks halfway up the layer to use as a guide.) Top the half-layer with lemon curd, and then put the top half back on and cover with lemon curd as well.
Cut the second layer in half and continue to fill with lemon curd and stack, ending with the top layer of cake, which you leave bare.
Cover the whole cake with lemon-flavored buttercream. Then using a piping bag, pipe dots of lemon curd of varying sizes on top and drizzle lines of lemon curd down the sides.
Pull away the wax paper, and voila--your lemon cake showstopper!
My favorite lemon curd recipe:
¾ cup sugar
2 tbsp lemon zest
¾ cup lemon juice (from 5-6 lemons)
1/8 tsp salt
½ cup unsalted butter, sliced in small pieces
Combine all the ingredients in a large saucepan and cook over
medium heat on the stove, while stirring, for about 7 minutes,
until the mixture starts to thicken. Immediately pass through
a fine-mesh sieve into a container. Press plastic wrap on the
surface of the curd and refrigerate for at least 2 hours.