Sweet and decadent lime cake soaked with a tequila syrup and layered with tart lime curd and creamy tequila lime buttercream.
Preheat oven at 350℉. Prepare 3-6" round cake pans with cooking spray and parchment paper.
In a stand mixer bowl combine the all-purpose flour, cornstarch, sugar, salt, and baking powder. Whisk together to de-clump the dry ingredients. Begin mixing on low with a paddle attachment.
Add butter to the dry ingredients, continue to mix on low until the mixture looks like sand. Then add the eggs one at a time and vanilla mix until fully incorporated. Scrape down the sides of the bowl.
Mix together the milk and lime juice and pour immediately into the batter. Add lime zest and blend on medium for 30 seconds until the batter is smooth and fluffy. Scrape down the sides of the bowl.
Evenly divide and pour the cake batter into 3 cake pans. Bake for 35-40 minutes or until a toothpick inserted into the center of each cake comes out clean or with just a few moist crumbs.
Remove cakes from the oven and let cool in pans for 10 minutes before inverting onto cooling racks to cool. Wrap cakes in plastic wrap and place into the freezer to chill for 30 minutes.
In a medium saucepan, whisk together the eggs, egg yolks, sugar, lime zest, and lime juice. Continue whisking over low-medium heat until the sugar has dissolved.
Add the cold butter cubes pieces at a time, stirring with a rubber spatula until each addition is melted and incorporated.
Continue cooking the mixture for 4-5 minutes until it is thickened and coats the back of a spatula. Press plastic wrap directly onto the surface to prevent a skin from forming. Set aside to fully cool.
In a small saucepan, combine the sugar and water over medium heat. Continue to heat for 5 minutes until the sugar has fully dissolved. Remove from the heat and add the tequila. Set aside to cool.
In a small saucepan, whisk together lime juice, cornstarch, and lime zest and place over medium heat. Begin to boil while stirring with a rubber spatula. Continue to mix until the mixture has become thick and transparent. Set in the fridge to cool thoroughly.
In the stand mixer bowl fitted with the paddle attachment, beat the butter and cooled lime gel until light and fluffy, about 2 minutes.
Turn the mixer to low and gradually add the powdered sugar, followed by the tequila and salt. Mix until combined. Mix until incorporated completely. Scrape down sides of the bowl.
Turn the mixer to medium-high and beat the frosting for about 5 minutes until light and fluffy. Add a tiny dot of green and yellow gel food color as needed. Then turn the mixer on low and mix for 2 minutes to push out any air bubbles.
Layer a chilled lime cake, cut side up onto cake board. Place a thin layer of buttercream on top of the cake then pipe a ring of lime buttercream. Add 1/4 cup of lime curd inside the circle of lime buttercream. Place another cake layer cut side down over the top. Repeat process for another layer.
Crumb coat and freeze for 20 minutes. Then add a thicker layer of frosting and smooth the sides out using a bench scraper. Finally, add the thin lime slices and sprinkle sea salt on top.