Combine lemon juice and sugar in a small saucepan. Cook the mixture over medium-high heat until sugar has dissolved, stirring occasionally. Remove from heat and let cool to room temperature.
For Cake:
Spray loaf pans with nonstick spray (see note). Set aside.
Combine butter, sugar, vanilla, salt, baking powder, and lemon zest in the bowl of a stand mixer. Beat on medium speed until light and fluffy, at least 6 minutes.
Add eggs, one at a time, allowing the egg to completely incorporate after each addition before adding the next. Scrape down the sides of the bowl. Beat the mixture on medium-high speed until light and airy, about 3 minutes.
Add flour and use a silicone spatula to incorporate it gently by hand so as not to deflate the batter.
In a small bowl, beat cream by hand to stiff peaks (see note). Add whipped cream to mixer bowl and gently fold in with a silicone spatula until no streaks of white remain.
Divide batter between loaf pans, filling each about half way, smoothing the top of the batter. Bake 15-20 minutes (see note), or until a toothpick inserted in the center comes out clean. Let stand 5 minutes in the pan, then invert the cakes from the pan onto on a wire rack (cakes should be upside down).
While cakes are still warm, spoon about ½ tablespoon of lemon syrup onto each cake (they should still be upside down). Allow cakes to cool to room temperature.
For Meringue:
In the bowl of a stand mixer, combine egg whites, sugar and salt. Set bowl over a small saucepan of simmering water, taking care to ensure the water doesn't touch the bottom of the bowl. Stir mixture until sugar is completely dissolved.
Once sugar is dissolved, transfer bowl to the mixer fitted with the whisk attachment. Add vanilla extract. Beat meringue on medium-high until it is white, fluffy, glossy, and the bowl has cooled to the touch. Meringue will hold stiff peaks.
Decorating:
Turn the cakes back right-side-up, and then you can pipe or spread the meringue onto the pound cakes however you like. For the piping that I did, you don't even need a piping tip, just cut the end of a piping bag or corner of a zip-top bag. After adding meringue to each of the cakes, toast the meringue (see note).Enjoy!
Notes
Note on pan and bake time: I used a mini loaf pan (link here). The cavities in my pan are 2.5" x 4". You can certainly use a different size pan(s), but you will need to adjust the bake time accordingly (the larger the pan the longer the bake time)!Note on zester: Most people have a grater of some kind in their kitchen, I just really love mine, so thought I'd give you the link (here). I love my microplane and they last forever!Note on whipping cream: Yes, really. By hand. ⅓ cup of cream just isn't enough for the mixer to actually accomplish the job. I hated it, but I did it, and so can you! If you have a hand mixer, that would do the job!Note on juicer: A juicer isn't a necessity in the kitchen, but it can make things easier. I was never interested in owning one until I made my first key lime pie (hand-squeezing 30+ tiny limes will do that). The one I use is from OXO (link here).Note on lemon syrup: The lemon syrup is very tart! If you want a more subtle lemon flavor, you can forgo the syrup. The pound cakes will still be delicious without the addition.Note on cake flour: You can use all-purpose flour for this recipe if you don't have/can't find cake flour, but the texture will not be as light and the crumb will not be as soft. If you can't find cake flour at your local grocery store and you'd like to use it, you can find it online (link here).Note on toasting meringue: I use a kitchen torch to toast my meringue. If you don't have a torch, you can put the loaves under the broiler, just don't take your eyes off them for a second! I prefer the torch, since it gives me more control over the toasting. My torch is so old I don't even know what kind it is, but this one (link here) online has great reviews.