Luscious Triple Layer Lemon Cake

I made this cake for Jim for Valentine's Day.  He loves anything citrus and this was a wonderful choice.  The cake layers are lemon-flavored, there is a lemon filling, and, of course, a lemon cream frosting.  The recipe may seem daunting, but each of the three parts can be made ahead and then assembled in a snap.  You could make the three cakes and wrap in plastic wrap the day ahead or even freeze and the filling and frosting could easily be made a few days ahead and just kept covered.  Easy-peasy.

LUSCIOUS TRIPLE LAYER LEMON CAKE

Lemon Cake:

1 cup unsalted butter (softened)
4 eggs
2 1/3 cups AP flour
1 1/2 tsp baking powder
1/2 tsp baking soda
1/4 tsp salt
2 cups sugar
2 tsp lemon peel
2 Tbsp lemon juice
1 cup buttermilk

Butter and eggs should sit at room temp for 30 minutes.  In a large bowl, stir together flour, baking powder, baking soda, and salt.  In stand mixer (hand mixer will work, too), beat butter until fluffy.  Add sugar, lemon peel/juice until combined.  Add eggs, one at a time, beating until just combined.  Add flour mixture and buttermilk alternately.  Pour batter equally into three 9" cake pans.  Bake 25-30 minutes at 350F.  Cool in pans 10 minutes, then remove to racks to cool completely.

Lemon Filling:

1/2 cup sugar
1 Tbsp cornstarch
1 1/2 tsp lemon peel (I use a rasp....all lemon peel in recipe should be finely shredded)
3 Tbsp fresh lemon juice
3 Tbsp water
3 beaten egg yolks in small separate bowl
1/4 cup unsalted butter, cubed

In a small saucepan, stir sugar, cornstarch, lemon peel, lemon juice, and water.  Cook and stir over medium heat until thick.  Remove from heat and let cool slightly.  Then slowly add half of the lemon mixture to the egg mixture.  This tempers the eggs to avoid cooking them before incorporating.  

Return to heat and cook on medium until it boils.  Cook for two minutes, stirring constantly.  Remove from heat and add butter.  Let filling cool before putting on cake.  If storing filling in refrigerator, place plastic wrap directly on top of filling to avoid a film build-up.

Lemon Cream Cheese Frosting:

1 tsp lemon peel
8 oz cream cheese, softened (fat-free not recommended)
1/2 cup unsalted butter, softened
1 tsp lemon juice
4 3/4 cups sifted powdered sugar (may need more depending on consistency of icing)

In stand mixer, beat cream cheese, butter, and lemon juice until fluffy.  Gradually add powdered sugar.  Stir in lemon peel.

Cake Assembly:

Place lemon filling between layers, and ice top and outside of cake with frosting.