Step 1

Preheat oven to 350 degrees F and grease a 9x13-inch.

Step 2

In a large bowl, mix together butter, buttermilk, and eggs until light and smooth. Slowly add in cake mix then fold in lemon zest.

Step 3

Transfer batter to the prepared baking dish and bake for 25-30 minutes, or until an inserted toothpick comes out clean.

Step 4

Allow cake to cool.

Step 5

Frosting: Add butter, cream cheese, and vanilla to a large bowl and mix until light and smooth.

Step 6

Slowly add in powdered sugar until well combined, then mix in lemon zest.

Step 7

Once the cake has fully cooled, use a wooden spoon handle (or other dowel) to poke holes in the surface of the cake.

Step 8

Spoon lemon curd into a piping bag, or ziplock with the corner cut off, and fill each hole with lemon curd.

Step 9

Spread cream cheese frosting over cake, then spoon remaining lemon curd on top. Use a knife to carefully swirl the frosting and lemon curd together in a marbled pattern.

Step 10

Chill cake until ready to serve.