Converted best-ever lemon meringue cake

Directions

1. Gluten-free lemon cake
2. Preheat the oven to 350 degrees. Line 2 round 9-inch cake pans with parchment and spray lightly with cooking spray.
3. Beat the sugar and eggs in a large bowl of an electric mixer at medium speed for 1 minute. Add all flours/starches, salt, baking powder, xanthan gum, oil, milk, vanilla, and lemon zest; beat at medium speed for 1 minute.
4. Pour batter into prepared pans. Bake for 25 minutes or until cake is firm and the center springs back when touched. Cool on wire racks in the pan for 5 minutes, then use a small knife to cut around the sides of the pan to loosen. Invert the cakes, peel off the parchment and cool completely. You will need to divide each of these two layers in half, making 4 layers total

1. Lemon syrup, caramel, lemon cream and meringue topping
2. Caramel: Pour the cream into a small, heavy saucepan. Split the vanilla bean in half lengthwise and use the tip of a sharp knife to scrape the seeds into the milk (or add the vanilla extract at this point). Place over medium-high heat and bring to just under a boil, stirring occasionally. Reduce the heat to low to keep the cream warm while you caramelize the sugar. In a large saucepan (much larger than you think you need--the caramel will boil very high when you add the cream later on), combine the 1 1/4 c. sugar, 1/4 c. water, 1/4 tsp. salt and corn syrup. Bring to a boil over medium heat, stirring to dissolve the sugar. Then cook, without stirring, until the mixture is amber colored, about 5-8 minutes. Remove from heat. Make sure your cream is closeby because the caramel will continue to cook once you take it off the heat. Carefully and slowly add the cream to the sugar syrup. The mixture will boil vigorously at first. Let the mixture simmer down, then whisk until smooth. Add the 3/4 tsp. lemon juice, then let cool for about 10 minutes. Cut the 4 tbsp. butter into 1-inch chunks and add them to the caramel one at a time, whisking constantly after each addition. Whisk the caramel periodically as it cools. You will end up with more than you actually need for the recipe, but consider this a good thing. A very, very good thing. Keep well-covered in the fridge.
3. Lemon syrup: combine the 1/3 c. sugar and 1/3 c. water in a small saucepan and bring to a boil, stirring frequently. When the sugar has dissolved, remove the pan from the heat, let cool for a few minutes and chill until cool to the touch, about 30 minutes. Whisk the 1/3 c. lemon juice into the syrup.
4. Lemon cream: Boil some water in a saucepan, then bring it down to a simmer. Combine the 1/2c. + 2 tbsp. lemon juice, 3 whole eggs, 1 egg yolk, 3/4 c. sugar and a pinch of salt in a stainless steel bowl that will rest securely in the rim of the saucepan over, not touching, the water. Do not let the egg yolks and sugar sit together without stirring; the sugar will mix with the yolks and become quite grainy. Whisk the ingredients until the mixture becomes very thick and registers 180 degrees on a thermometer. Remove the bowl from over the water and let cool to 140 degrees, stirring from time to time to release the heat. Meanwhile, cut the 1 c. butter into 1-inch chunks. When the cream is ready, use an immersion blender to add the butter 1 tablespoon at a time, blending until incorporated after each addition. The cream should be pale yellow and opaque and thick at this point. You can use the cream immediately or pour it into a storage container with a tight fitting lid. If you want to save this for later use, you can refrigerate for up to 5 days and reheat gently in a stainless steel bowl set over simmering water until it has softened
5. Assembly + meringue: Line the sides of a 9-inch springform pan with 3-inch sides with plastic wrap, allowing enough overhang to cover the top of the cake completely once it's assembled. I find it's easiest to do a piece of saran going each way over the springform without the bottom in it and then drop the bottom in. You want the saran to be going underneath the pan bottom so it only touches the sides. Fit one cake layer into the bottom of the pan. Using a pastry brush, moisten the layer evenly with 1/4 of the lemon syrup. You may want to use more syrup on the top layers and less on the bottom because it does seep down overnight. Then, cover the layer with 1/3 c. of caramel, then 3/4 c. of the lemon cream. Repeat with the next two layers. Top with the last cake layer, moisten it with syrup, and fold the overhanging plastic wrap over it to seal. Refrigerate for at least 4 hours or up to overnight. When you are ready to finish the cake, make the meringue. Boil water in a saucepan over medium heat. Combine the egg whites, 1 3/4 c. sugar and pinch salt in the bowl of a stand mixer that will rest securely in the rim of the saucepan over, not touching, the water. Whisk together and then place over the the water. Continue to whisk until the whites are hot to the touch (120 degrees). Remove the bowl from over the water and place on the mixer stand. Using the whisk attachment, mix on high speed until the mixture is very thick and holds glossy, stiff peaks. Retrieve your cake. Release and list off the pan sides and peel away the plastic wrap. Transfer onto your serving plate. Immediately frost your cake with the meringue, creating swoops and peaks with your offset spatula. If you'd like, you can create more peaks by using your fingers to pull away at the meringue (which is what I did). Using a kitchen torch, lightly brown the meringue, blackening some of the peaks. The cake can be served immediately or kept cold in the fridge until ready to serve, up to 1 week.