2 cups (10 ounces or 285 grams) all-purpose flour
1 cup (7 ounces or 200 grams) packed light brown sugar
3/4 teaspoon salt
1/2 teaspoon baking powder
1/4 teaspoon baking soda
16 tablespoons (8 ounces or 225 grams) softened unsalted butter, plus more for greasing the pan
1/3 cup (3 ounces or 85 grams) chunky peanut butter

For the Filling
1 cup (9 ounces or 255 grams) chunky peanut butter
8 tablespoons (4 ounces or 115 grams) unsalted butter, softened
1/2 cup (2 ounces or 55 grams) confectioners’ sugar
2 teaspoons vanilla extract
pinch salt
2/3 cup (160 mL) black currant jam