The classic childhood sandwich is dessert form!
Preheat oven to 350F. Grease a 9" × 13" baking pan. Line with parchment paper, then grease and flour.
In the bowl of a standing mixer fitted with the paddle attachment, beat butter and sugar on medium speed until smooth. Mix in eggs, vanilla and peanut butter until combined.
In a separate large bowl, whisk together flour, baking powder and salt. Gradually add to peanut butter mixture and mix on low speed until combined.
Spread 2/3 of the dough into the prepared pan. Evenly spread jam on top. Drop small, flattened pieces of remaining dough on top to cover the jam layer. Sprinkle on peanuts.
Bake 30-35 minutes until golden brown. Enjoy!