Crockpot Hot Fudge Cake

1 3/4 C. packed light brown sugar, divided 2 C. flour 1/4 C. plus 3 Tbsp. cocoa, divided 2 tsp. baking powder 1 tsp. salt 1 C. milk 4 Tbsp. (1/2 stick) butter, melted 1 tsp. vanilla 3 1/2 C. boiling water Coat crockpot with nonstick cooking spray. Mix 1 C. brown sugar, flour, 3 Tbsp. cocoa powder, baking powder, and salt in medium bowl. Stir in milk, butter, and vanilla. Mix until well-blended. Pour into crockpot. Blend remaining 3/4 C. brown sugar and 1/4 C. cocoa powder in small bowl. Sprinkle evenly over mixture in crockpot. Pour in boiling water, but DO NOT STIR. Cover, cook on high 1 1/4 to 1 1/2 hours or until toothpick inserted into center comes out clean. Allow cake to rest 10 minutes, then invert onto serving platter or scoop into serving dishes. Serve warm; dust with cocoa powder, if desired. When I made this, it didn't set up all the way cooking the time suggested, but was still pretty tasty, especially served warm with vanilla ice cream (kind of like thick hot fudge sauce poured over top). So maybe cook it longer?