Step 1

Preheat the oven to 350°F and set an oven rack in the middle position. Line a 9x13-inch cake pan with heavy-duty aluminum foil, leaving an overhang on all sides for easy removal. Lightly coat the foil with nonstick cooking spray.

Step 2

In a medium bowl, whisk together the flour, baking powder, and salt.

Step 3

In the bowl of an electric mixer fitted with the paddle attachment or beaters, beat the butter and sugar on medium speed until light and fluffy, about 3 minutes. Scrape down the sides of the bowl and add the eggs, one at a time, beating after each addition. Add the peanut butter and vanilla, scraping down the bowl as necessary, and beat until evenly combined, about 30 seconds. Scrape down the bowl again and add the flour mixture; mix on low speed until just combined, about 30 seconds.

Step 4

Set aside about 1½ cups of the dough for the topping. Spread the remaining dough evenly into the prepared cake pan using an offset spatula; alternatively, use your fingers, lightly dusted with flour, to press it in. Spread the jam evenly over the dough, maintaining a ¼-inch border around the edges. Using a spoon, stir the chopped peanuts into the reserved dough. Using a teaspoon and your finger, drop the dough in ½- to 1-inch clumps over the jam, allowing some jam to peek through. Bake for about 40 minutes, until the top is lightly golden. Allow to cool completely on a wire rack. Lift the dessert out using the foil edges, transfer to a cutting board, slice into squares, and serve.

Step 5

Make-Ahead/Freezer-Friendly Instructions: The bars can be made up to two days in advance and stored at room temperature in an airtight container. For longer storage, they can be frozen for up to three months. To freeze, allow the bars to cool completely, then wrap each bar individually or group several together—depending on your future serving needs—in plastic wrap. Place the wrapped bars in a resealable freezer bag or an airtight container. When ready to enjoy, remove the desired amount from the freezer and let them thaw at room temperature for a few hours or overnight.