01 - Set oven to 400°F. Line a baking sheet with parchment paper.
02 - Toss pitted, halved cherries with sugar and vanilla. Spread on prepared sheet and roast 12-15 minutes until juicy and caramelized. Cool completely.
03 - Reduce oven to 350°F. Grease an 8-inch square pan and line with parchment, leaving overhang for removal.
04 - Set heatproof bowl over simmering water. Melt butter and chocolate, stirring until smooth. Remove from heat and cool slightly.
05 - Whisk granulated and brown sugars into melted chocolate. Add eggs one at a time, then stir in vanilla and salt.
06 - Sift flour and cocoa into batter. Gently fold until just combined, being careful not to overmix.
07 - Fold most roasted cherries into batter, reserving a few pieces for topping.
08 - Pour batter into prepared pan, smooth top, and scatter reserved cherries. Bake 25-28 minutes until toothpick comes out with moist crumbs.
09 - Cool completely in pan before lifting out and cutting into squares.