Step 1

Preheat the oven to 350℉. Grease an 8-inch square baking pan and line it with parchment paper. Set it aside.

Step 2

Whisk the flour, sugar, baking soda, baking powder, salt, and lemon zest in a large bowl.

Step 3

Whisk the buttermilk, eggs, cooled melted butter, and vanilla bean paste in a medium bowl. Make a well in the center of the dry ingredients and pour the wet ingredients inside the well. Whisk the batter until smooth and combined.

Step 4

Pour the batter into the prepared cake pan. Smooth out the batter into an even layer. Tap the cake pan gently on the counter to remove any air bubbles. Bake the cake for 35 to 40 minutes, or until a toothpick inserted into the center of the cake comes out clean.

Step 5

Let the cake cool completely. Spread the 10oz jar of lemon curd over the cooled cake.

Step 6

Using an electric mixer, beat the butter and cream cheese until light and fluffy, about 3-4 minutes. Add the sifted powdered sugar, salt, and vanilla extract. Beat on medium speed until incorporated and smooth. Bring the speed to high and whip the frosting until fluffy, about 3 minutes.

Step 7

Transfer the frosting to a piping bag. Pipe the frosting over the lemon curd. Using an offset spatula, carefully smooth out the frosting to cover the cake.

Step 8

Enjoy a slice of cake cold or at room temperature. Store the cake in the refrigerator for up to 4 days.