Peanut Butter Blackberry Bars

Step 1

Heat oven to 350 degrees. Butter an 8- or 9-inch square pan and line with parchment paper, leaving a 2-inch overhang on two of the sides.

Step 2

In a large bowl, stir together butter, peanut butter, brown sugar and 1/2 cup granulated sugar until smooth and creamy. Add egg and vanilla and beat to combine. Add flour, salt and baking powder and stir to combine.

Step 3

Press about two-thirds of the dough into the prepared pan. In a separate bowl, toss berries with remaining 1/4 cup granulated sugar. Scatter berry and sugar mixture over dough, then crumble remaining dough over top, pulling it apart into big crumbs.

Step 4

Bake on the middle rack until golden brown, 45 to 50 minutes. Sprinkle with flaky salt, if using. Let cool completely before slicing into squares. Store, covered in the refrigerator, for up to 3 days.