Prepare a 9x9 baking dish with aluminum foil or parchment paper.
Preheat the oven to 350 degrees and line a rimmed baking sheet with parchment paper.
Spread the cake mix to a thin layer and toast for 5 minutes to kill off the bacteria. Set it aside and allow it to cool while you make the fudge.
In a large microwave-safe bowl, mix together the sweetened condensed milk and white chocolate chips.
Microwave the chocolate for 1 minute and then stir vigorously allowing the morsels to continue melting from the residual heat.
If needed, return the bowl to the microwave for 15 seconds at a time, stirring well between each heating. Do not overheat.
To the melted chocolate, add the cake mix and stir well to blend.
Fold the pineapple into the fudge batter.
Transfer the fudge to the prepared dish and smooth evenly.
Press the cherries into the fudge.
Refrigerate the fudge overnight prior to slicing into pieces and serving.