Ingredients

For the cake: 

• 1 cup cake flour

• 1 1/2 tsp baking powder

• 1/4 tsp baking soda

• 1/4 tsp ground ginger

• 1/4 cup salted butter; softened

• 1/4 cup peanut butter

• 2/3 cup brown sugar

• 1 egg

• 1/2 cup + 2 tbsp whole milk

For the simple syrup 

• 1/2 tbsp ginger; grated

• 1/2 cup water

• 1/2 cup brown sugar

For the frosting

• 3/4 cup salted butter; softened

• 1/2 cup peanut butter

• 2 cups powdered sugar

Instructions

1. Preheat the oven to 350 degrees.

2. Start the simple syrup in a small saucepan, add the sugar, water, and ginger. On medium heat, bring to a simmer and stir continuously to prevent the sugar from burning on the bottom of the pan. Simmer for about 5 minutes until the sugar dissolves and the mixture is slightly thickened.

3. Pour the simply syrup into a glass jar or bottle and chill in the refrigerator for 1 hour.

4. In the bowl of an electric mixture, add the butter, peanut butter, and brown sugar. Cream together on medium speed for about 2 minutes until fluffy. Add the egg and beat until combined.

5. In a bowl, whisk together the cake flour, baking powder, baking soda, and ginger.

6. On medium speed, alternate between the flour and milk, adding a small amount each time and fully incorporating between each addition. Stop mixing immediately after the last addition is incorporated.

7. Line a 9” by 13” baking sheet with parchment paper. Pour the batter onto the pan and use a spatula to make sure it is spread in an even layer. Bake for 25 minutes or until a fork comes out clean. Let the cake cool for about 25 minutes. Use a fork to poke the cake about 20 times. Use a pastry brush to cover the cake with a layer of simple syrup. Let the syrup soak in for 5 minutes and add another layer. Repeat this process until the simple syrup is gone.

8. Chill the cake for 20 minutes in the freezer and then remove from the pan and cut the sheet into 12 even sized squares.

9. In the bowl of an electric mixer, add the butter and peanut butter. Beat on medium-high speed for two minutes to combine the butter and peanut butter. On low speed, add the powdered sugar 1/2 cup at a time, thoroughly combining between additions.

10. Add the frosting to a piping bag fitted with 1/2 inch circle tip. Use the piping bag to outline the edge of a cake square and fill in the middle. Use a butter knife to spread the frosting into an even layer. Repeat the process with two more layers of cake.

11. Place the cakes on a baking sheet and cover with plastic wrap. Chill in the freezer for 30 minutes. Take the cakes out of the freezer and thinly frost the exterior with the remaining frosting.