Preheat your oven to 350°F (175°C) and prepare a 9x9-inch baking pan with aluminum foil and cooking spray.

Beat the softened butter with an electric mixer until smooth and creamy.

Add the strawberry cake mix and large egg, mixing on low speed until a thick dough forms.

Reserve one-third of the dough for topping, then press the remaining dough into the bottom of the pan.

Sprinkle the white chocolate chips evenly over the pressed dough base.

Drizzle the sweetened condensed milk over the layer of white chocolate chips.

Crumble the reserved dough over the top of the drizzled condensed milk.

Bake for 27-30 minutes, until edges are set and center is slightly jiggly.

Allow cooling for at least 2-3 hours at room temperature before slicing.