Preheat oven to 350°F (175°C) and line an 8x8-inch baking dish with parchment paper.
In a large bowl, combine cake mix, egg, and melted butter. Mix until a thick dough forms.
Press two-thirds of the dough evenly into the prepared baking dish.
Drizzle sweetened condensed milk over the dough.
Sprinkle white chocolate chips and diced strawberries evenly on top.
Crumble the remaining dough over the top.
Bake for 30 minutes or until the top is golden brown.
Let cool completely before slicing into bars.