The slow cooker makes this moist chocolate brownie a cinch to prepare. For the topping, dark sweet cherries are simmered with maple sugar to yield a glossy crimson sauce. If you’re trying to avoid caffeine, omit the espresso powder.
1 1/2cups frozen dark sweet pitted cherries, divided
1 tsp arrowroot flour
Mist a 1½-quart baking dish with cooking spray. (NOTE: Baking dish should be able to fit inside your slow-cooker insert.) In a medium bowl, whisk together flour, cocoa, espresso (if using), all but 2 tbsp maple sugar, baking powder and 1/4 tsp salt until well combined.
In a second medium bowl, stir together milk, 1/2 cup water, oil and 1 tsp vanilla. Pour milk mixture into flour mixture and stir until a smooth batter forms. Pour into baking dish. Place dish inside slow cooker; cover and cook on high until top of brownie is completely set and a toothpick comes out clean, 2 to 2½ hours.
Meanwhile, in a medium saucepan, add 1 cup cherries plus 1/2 cup water, remaining 2 tbsp maple sugar and remaining 1/4 tsp salt. Bring to a boil on high and cook, mashing with a potato masher or wooden spoon, until most of the cherries have broken down, about 7 minutes.
In a small bowl, whisk together arrowroot and 1 tsp water until well combined. Stir arrowroot mixture, remaining 1/2 cup cherries and 1 tsp vanilla into sauce; boil until thickened, about 2 minutes. Serve in ramekins and top each portion with cherry sauce.