Line a 13x9 baking sheet with parchment or waxed paper and set aside.
Using a saucepan on the stove, medium heat, melt the butter and sugar together. Once melted, add in the heavy whipping cream and stir. Bring the mixture to a boil and allow bubbling for 5 minutes. Be sure to stir frequently while the butter mixture is boiling.
Pour into a large bowl, add in the white chocolate chips, marshmallow fluff and blend until combined. The chocolate chips do not need to be pre melted; the hot butter mixture will melt them.
Scoop half of the mixture out onto the prepared baking sheet and spread out to the edges.
Pour the strawberry jello powder into the remaining mixture and stir until combined.
Pour the strawberry layer on top of the bottom layer and spread out to the edges. Swirl with a chopstick if you like.
Top with sprinkles if you wish. (as shown)
Cool in the fridge overnight to completely set the fudge. Cut and serve! Store in an airtight container.