Combine all the ingredients in a large mixing bowl: cake mix, water, oil, eggs, pumpkin puree, pumpkin pie spice and espresso powder. Beat well until combined.
Pour the batter into a 9-inch by 13-inch pan. Bake at 350° F for about 20-24 minutes. Test the cake for doneness by inserting a toothpick into the middle of the cake. If the toothpick comes out clean, your cake is done.
Allow the cake to cool for at least 30 minutes. Use a wooden spoon or another round object and poke holes all over the top of the cake.
For the Filling:
In a microwave-safe bowl, heat the water for 60-90 seconds until it’s just about boiling. Stir in the espresso powder and mix until the powder is dissolved.
In a small mixing bowl, combine the sweetened condensed milk and the brewed espresso. Whisk until well combined. Pour the mixture over top of the cake, spreading evenly. Allow the milk to absorb into the cake.
For the Topping:
In a microwave-safe bowl, heat the water for 60-90 seconds until it’s just about boiling. Stir in 1 teaspoon espresso powder and mix until the powder is dissolved. Place in the freeze for 5-10 minutes to cool.
Place the metal mixing bowl and whisk in the freezer for 5-10 minutes to chill.
Pour the heavy cream into the chilled bowl and beat on medium-high speed for 2 minutes.
Next add the brown sugar, cinnamon and 1 teaspoon espresso powder. Continue beating on high speed until soft peaks start to form.
Slowly add the powdered sugar and mix into the whipped cream until incorporated and then increase the mixing speed to high until stiff peaks form.
Spread the whipped cream over the cooled cake. Drizzle with caramel sauce if desires. Keep this cake refrigerated once the whipped cream has been added.
This cake can be prepared in advanced as long as it’s refrigerated.