• Preheat the oven to 350 degrees.
• Grease and flour two 8 inch round pans. Combine all ingredients and beat with hand mixer until smooth and combined.
• Divide the batter between the two pans.
• Bake in the preheated oven for 21 minutes, or until a toothpick inserted into the center of the cake comes out clean.
• Allow to cool in pans on wire racks for 10 minutes. Then invert onto wire racks to cool completely.

To make filling:

• In a medium saucepan, mix together 1 tablespoon lemon zest, 1/2 cup lemon juice and 1 tablespoon cornstarch until smooth.
• Mix in 6 tablespoons butter and 3/4 cup sugar, and bring mixture to boil over medium heat.
• Boil for one minute, stirring constantly.
• In a small bowl, with a wire whisk, beat egg yolks until smooth.
• Whisk in a small amount of the hot lemon mixture.
• Pour the egg mixture into the saucepan, beating the hot lemon mixture rapidly.
• Reduce heat to low; cook, stirring constantly, 5 minutes, or until thick (not to boil).
• Pour mixture into a medium bowl.
• Press plastic wrap onto the surface to keep skin from forming as it cools. Cool to room temperature. Refrigerate 3 hours.

Lemon Frosting:

• In a standing mixer, beat powdered sugar, 1/2 cup butter, heavy whipping cream, 2 tablespoons lemon juice and 1 teaspoon lemon zest until smooth, and increase speed and continue to beat until light and fluffy

Building the cake:

• Using a cake leveler, split each cake layer in half horizontally, making 4 layers.
• Place 1 layer, cut side up, on a serving plate.
• Spread with half of the lemon filling.
• Top with another layer, and spread with 1/2 cup frosting.
• Add the third layer, and spread with the remaining half of the lemon filling.
• Place the last layer of cake on top.
• Scoop remaining frosting into the piping bag and pipe dollops completely covering the cake.