Heat oven to 325°F. Spray an 8" x 8" baking pan with cooking spray and line with parchment paper, leaving the paper overhanging on 2 sides; spray paper with cooking spray.

In large heatproof bowl, melt chocolate with oil over simmering water. Whisk in sugar and dried plum purée until mixed; whisk in eggs and vanilla. Fold in flour and salt just until blended; fold in walnuts.

Scrape batter into prepared pan, spreading it evenly.

Bake about 30 minutes or until a cake tester inserted into the brownies comes out clean. Cool in pan at least 10 minutes; remove from pan and cut into 2-inch squares.