Spray the interior of a crock pot basin with PAM baking spray.
In a medium mixing bowl, whisk together flour, Dutch Process cocoa powder, sea salt flakes and baking powder, set aside.
Add melted butter, vanilla, and brown sugar to mixing bowl. Beat the butter with the sugar until creamy.
Spoon in the cocoa mixture and gradually incorporate the milk and heavy cream. Batter will have the consistency of brownie batter.
After all wet ingredients have been added and mixed in, fold in the semisweet chocolate chips. Scoop batter into Crock Pot and spread in an even layer.
In a separate bowl, prepare the lava sauce by whisking Dutch Process cocoa powder and brown sugar together. Sprinkle mixture evenly on top of cake batter in the crock pot. Do not mix.
Bring water to a boil and pour evenly over the lava sauce layer. Do not stir.
Cover the crock pot, set temperature to High, and set the timer for 2 hours. Check at the 2 hour mark. Deeper, narrow-based crock pots may require additional time, but do not exceed 2 hours and 30 minutes. Chocolate Lava Cake will be ready when the top of it appears sponge-like.
Serve warm (preferably in a bowl or mug) with vanilla ice cream.