01 -
Grease the insert of a large (5 to 7-quart) crock pot with cooking spray.
02 -
Combine the sugar, flour, unsweetened cocoa, baking powder, and salt in a large bowl.
03 -
Whisk the milk, melted butter, and vanilla into the dry ingredients until smooth.
04 -
Spread the batter evenly in the bottom of the greased crock pot insert.
05 -
Whisk together granulated sugar, light brown sugar, and cocoa powder.
06 -
Sprinkle the fudge sauce mixture evenly over the batter. Carefully pour the boiling water over the top without stirring.
07 -
Cover with the lid and cook on high heat for 2 to 2 ½ hours or on low heat for 3 ½ to 4 hours. The cake is ready when a toothpick inserted into the center comes out mostly clean.
08 -
Turn off the heat, remove the lid, and let the cake sit for 15 minutes to cool slightly. Serve warm with whipped cream or vanilla ice cream.