Combine heavy cream, sugar, pumpkin puree, pumpkin pie spice and remaining egg & flour in a mixing bowl. Stir until smooth.
Pour the pumpkin batter over the cooked brownie batter.
Stir a tablespoon of water into the remaining brownie batter, then use a spoon to scoop it into the pumpkin batter, swirling as you go.
Bake for 40-45 minutes, until the top is set.