Preheat the oven to 350 degrees F. Prepare the cake batter as directed, substituting corn liquid for the water in the mix. Linetwo 12-cup muffin pans with paper liners. Divide the batter between the pans, filling each cup two-thirds of the way. Bake as directed; let cool completely.
Meanwhile, put the white chocolate in a microwave-safe bowl and microwave in 15-second intervals, stirring, until smooth. Pour over the popcorn in a large bowl; toss to coat, then refrigerate until set, about10 minutes. Remove about 2 cups of the white chocolate popcorn and crush.
Beat the heavy cream and confectioners' sugar in a bowl with a mixer on medium-high speed until soft peaks form, about 2 minutes. Fold in the crushed popcorn.
Frost each cupcake with 3 tablespoons of the popcorn whipped cream. Top with the remaining white chocolate popcorn.