Lemony Lemon Cake

Ingredients

For cake (Make sure all your ingredients are at room temperature)
• 1 cup (120g) sorghum flour
• 3/4 cup (110 g) sweet rice flour
• 1 1/4 cup sugar
• 1 cup butter
• 1 cup buttermilk
• 1/2 tsp salt
• 2 tsp baking powder
• 1/4 cup lemon juice
• 2 tbsp. lemon zest
• 5 large eggs
For the syrup
• 1/4 cup white granulated sugar
• 1/4 cup lemon juice
• 1 tbsp water
For frosting
• 1 cup mascarpone
• 1 tbsp lemon juice
• 1 cup whipping cream
• 1 cup icing sugar
For Lemon curd (you only need half of this recipe)
• 4 large egg yolks
• 1/2 cup granulated sugar
• 2 tbsp lemon zest
• 1/3 cup freshly squeezed lemon juice
• 1/8 teaspoon fine salt
• 6 tablespoons unsalted butter, cut into 6 pieces, at room temperature

Instructions

1. Preheat the oven to 350°F and set an oven rack in the middle position. Brush a 9x13" pan with butter and then line with parchment paper.
2. In a medium bowl, whisk together the sorghum and sweet rice flour, baking powder, lemon zest and salt. Set aside.
3. In the bowl of an electric mixer fitted with the paddle attachment, cream the butter and sugar on medium speed until light and fluffy, 3-4 minutes.
4. Scrape down the sides of the bowl, then beat in the eggs one at a time, beating well after each addition. Scrape down the sides of the bowl again.
5. In another bowl, combine the buttermilk, and lemon juice.
6. With the mixer on low speed, beat in one-quarter of the flour mixture, then one-third of the buttermilk mixture. Beat in another quarter of the flour, then another third of the liquid mixture.. Repeat with another quarter of the flour and the remaining buttermilk mixture. Finally, beat in the remaining flour mixture.
7. Scrape down the sides of the bowl, and give a quick mix to make sure all of the ingredients are well incorporated.
8. Spoon the batter into the prepared pan and smooth with a rubber spatula. Bake for 35 minutes, or until a cake tester comes out clean.
9. Cool the cake in the pan for ten minutes on a rack.
10. Meanwhile, make the syrup. Combine the water, lemon juice and sugar in a saucepan and heat over a medium heat, stirring occasionally, until the sugar has dissolved. Raise the heat, boil for 4 min until slightly reduced and syrupy, then remove from the heat.
11. Set the cooling rack on top of the cake pan with the feet of the cooling rack facing up. Flip the cake pan over so the cooling rack is on the bottom and the inverted cake pan is on top.Peel the parchment paper from cake.
12. Prick cake several times with a skewer. Brush the sides and tops of the cake with the syrup, allowing a couple of minutes between brushing to allow syrup to absorb into cake, until the syrup is gone. Cool the cake completely.
13. Transfer the cake to a large plate or cutting board. Trim the sides of the cake for a neat look. Spoon (3/4th) of the frosting over the top of the cake. Use offset spatula to spread frosting all the way to the edges of the cake. Put lemon curd in a piping bag or use a freezer bag and cut a small hole of desired thickness..
14. Create a criss cross pattern holding the bag at a 45 degree angle. Then holding the bag vertically with the tip of the bag close to the surface, squeeze a little lemon curd to make a dot of the desired size to finish, stop squeezing, push down and then draw up sharply.
To make frosting
15. In a medium bowl combine mascarpone cheese, powdered sugar, lemon juice. Stir together until smooth, and set aside.
16. In the bowl of an electric mixer beat whipping cream until stiff peaks form, making sure you don't overdo it, the last thing you want is for it to curdle.
17. Gently fold the whipped cream, into the mascarpone mixture until combined. Then use immediately or keep in the fridge for later use.
For Lemon Curd (recipe source; Chowhound)
18. Fill a medium saucepan with 1 to 2 inches of water and bring it to a simmer over high heat; reduce the heat to low and keep the water at a bare simmer.
19. Place all of the ingredients except the butter in a large heatproof bowl and whisk to combine. Set the bowl over, but not touching, the simmering water and whisk constantly until the yolks thicken and the mixture forms ribbons when the whisk is lifted from the bowl, about 7 to 10 minutes.
20. Remove the bowl from the simmering water; whisk in the butter one piece at a time, waiting until each piece is completely melted and incorporated before adding another.
21. Set a fine-mesh strainer over a medium bowl. Strain the curd, pressing on the solids and scraping the extra curd clinging to the underside of the strainer into the bowl; discard the solids left in the strainer.
22. Press a sheet of plastic wrap directly onto the surface of the curd to prevent a skin from forming.
23. Refrigerate until set and chilled, at least 3 hours. (The curd can be made and refrigerated up to 5 days ahead.)