Preheat oven to 350 degrees F (180 degrees C). Line an 8 inch pan with parchment or aluminum foil and grease the bottom. This will make it easier to remove and cut your bars after they have baked.
Cream Peanut Butter (1 cup) and Unsalted Butter (1/2 cup) with a handheld mixer. Add Brown Sugar (1/2 cup) and mix until fluffy. Add the Egg (1) and Vanilla Extract (1 teaspoon). Mix until combined.
In another bowl, whisk All-Purpose Flour (1 3/4 cup), Baking Powder (1/2 teaspoon) and Salt (1/2 teaspoon) until incorporated.
Add the flour mixture to the peanut butter mixture a little at a time until crumbly.
Pour 3/4 of the mixture into the prepared pan and press down with your fingers. Pour Raspberry Preserves (1/2 cup) over this layer and crumble remaining batter over top.
Bake for 35-40 minutes. Let cool on a wire rack. Remove aluminum foil or parchment and cut into bars.
Enjoy with a tall glass of milk!