Preheat oven to 350F. Spray square cake pan and line with parchment paper, then spray again. Make the cake mix and fill the pan half full. Bake until a toothpick comes out clean, about 30 to 35 minutes.

Let the cake cool in the pan for 10 minutes, then turn onto a rack and cool completely. Transfer the cake to a work surface. Trim off the top using a serrated knife.

Using the same pan (unless you have another), repeat the steps above. We made 3 layers of cake from the box mix. As the cakes are cooling, make the peanut butter frosting.

In a medium bowl, combine the butter and peanut butter, beating with a mixer until smooth. Alternate adding the confectioners’ sugar and milk, beating after each addition, until the frosting is fluffy and smooth.

Carefully place a cake layer on a plate or stand.

Spread a thick layer of peanut butter frosting on the bottom cake layer, then spread the jam or jelly on top of the frosting. Top with a second cake layer. You can stop here if you’d like a peanut butter and jelly sandwich cake with only 2 layers, or continue like we did, and frost the second layer with peanut butter frosting and jelly, then top with the remaining cake layer.

Cut the cake in half diagonally and then each half into fourths to yield 8 small slices of cake. Watch those childhood dreams come true as you enjoy this tasty treat!