There are so many versions of these layered types of squares, but this one is unique in the way that it uses a store-bought boxed cake mix for the base. You don't need to bake the cake first! Deliciously sweet and sticky Caramel and Salted Nut Squares are so quick and easy to make!
Begin by preheating your oven to 350 degrees F. Line a 9×9 baking pan with parchment paper. Fold the parchment paper so that it fits snugly in the pan. I use two sheets – one folded to fit the length of the pan and another folded to fit across the pan. Allow the excess parchment paper to hang out over the side of the pan. Once the confection is firm, use the excess parchment to lift the whole block out of the pan to make it easy to cut into squares.
Add the boxed cake mix, coconut, and melted butter to a mixing bowl and use a fork to mix and combine. When the two are blended well enough, the mixture will resemble wet sand. Transfer the mixture to the prepared baking pan and gently press it into the pan to form an even layer.
Sprinkle over the mixed salted nuts and mini white chocolate chips in an even layer. Pressing them down gently will ensure that you have a neater square that is easier to slice.
Pour the sweetened condensed milk over the nuts and chocolate so that there is an even layer covering the entire surface.
Bake for 30 to 35 minutes or until the outer perimeter of the squares are lightly golden brown. (It's a good idea to check at the 20-minute mark. If the squares are getting too brown, you can loosely cover the pan with aluminum foil for the remainder of the baking time.)
Remove the baking pan from the oven and allow the squares to fully cool. I like to place the baking pan onto a wire cooling rack and let it sit undisturbed for at least 2 hours before slicing.