Peanut Butter and Jelly Bars

From Serious Eats. The original recipe is really, really rich. The kiddos couldn't finish their tiny bars I cut for them. I think I'll start to cut back on the sugar until we get something we like.

1 cup (2 sticks) unsalted butter, room temperature, plus more for pan
3 cups all-purpose flour, plus more for pan
1 1/2 cups sugar
2 large eggs
2 1/2 cups smooth peanut butter
1 1/2 teaspoons salt
1 teaspoon baking powder
1 teaspoon pure vanilla extract
1 1/2 cups strawberry jam, or other flavor
2/3 cup salted peanuts, roughly chopped

Heat oven to 350°F.
Grease a 9-by-13-inch pan with butter, and line the bottom with parchment paper.
Grease the parchment, and coat inside of pan with flour; set aside.
Place butter and sugar in the bowl of an electric mixer fitted with the paddle attachment.
Beat on medium-high speed until fluffy, about 2 minutes.
On medium speed, add eggs and peanut butter; beat until combined, about 2 minutes.
Whisk together salt, baking powder, and flour.
Add to bowl of mixer on low speed 1/3 of the amount at a time.
Add vanilla.
Transfer two-thirds of mixture to prepared pan; spread evenly with offset spatula (or fingers).
Using offset spatula, spread jam on top of peanut-butter mixture.
Dollop remaining third of peanut-butter mixture on top of jam.
Sprinkle with peanuts.