Preheat oven to 350 degrees and prepare a bundt cake pan with non-stick spray.
In a large bowl, mix together the cake mix, eggs, water, vegetable oil and jello mix until well combined. Pour the batter into your prepared pan.
Bake for 35-40 minutes, until a toothpick comes out clean. Cool for 10 minutes and then turn the cake over onto a cooling rack until completely cooled.
Once the cake is cooled, prepare the cream filling. It’s important to wait until the cake is cooled.
In a large bowl, cream the butter until it’s light and fluffy. Add in the fluff, powdered sugar and vanilla and mix until well combined. Slowly add in the heavy whipping cream and mix after each tbsp. Stop adding the heavy cream once the consistency is creamy enough to be piped.
Carefully turn the bundt cake over on it’s top.
Using a teaspoon, small cookie scoop or melon baller, scoop out 8-10 holes in the bottom of the cake. Using the end of a wooden spoon, push the holes a little deeper and create a nice space for the cream to fill.
Scoop the filling into a piping bag and fill each of the holes up with the cream filling.
To flip the cake back over, place your cake plate on top of the cake and carefully turn it back over. Dust with some powdered sugar, cut and enjoy!