Preheat oven to 350°F. Spray a 10” deep-dish pie pan with cooking spray.
In a large bowl, whisk together flour, ¼ cup Splenda® Sugar Blend, ¼ cup cocoa powder, baking powder, baking soda, salt, and cinnamon.
Stir in milk, oil, and vanilla extract. (Batter will be thick.) Spread batter in prepared pan.
In a small bowl, combine Splenda Brown Sugar Blend, remaining ¼ cup Splenda Sugar Blend, and remaining ¼ cup cocoa. Sprinkle this mixture evenly over the batter. Carefully pour hot water over the top.
Bake for 30–35 minutes or until cake is set on top and pudding starts to bubble up from the bottom. Cool in pan 10 minutes. Spoon into bowls and serve.