Preheat oven to 350° and line an 8x8 baking dish with parchment paper.
Combine the cake mix, oil, and eggs, until fully incorporated.
If adding any mix-ins, fold those in now (see notes).
Pour batter into prepared pan and bake approximately 10-15 minutes, or until the edges look set and the center has just a slight jiggle. A toothpick inserted into the center should come out with a thin layer of batter.
Cool completely.
Once fully cooled, top the brownies if desired (see notes).
Cut in to squares (or hearts!) and enjoy!
Notes
Suggested Mix-ins:
1 c. white chocolate chips, or
1 c. crushed Oreos (plus more for topping)
Suggested Toppings:
Cream cheese frosting (beat together 1 8oz block cream cheese, 1 stick butter, and 2 cups powdered sugar until desired consistency; thicken frosting by adding additional powdered sugar or thin frosting by adding a splash of milk)
White chocolate drizzle (melt white chocolate chips or melts, put in a piping bag or zip-top bag, cut off a corner and drizzle melted chocolate over top of cooled brownies)
White chocolate swirl (melt white chocolate chips or melts, spoon on top of batter in the prepared pan before baking, using a butter knife, swirl the white chocolate into the brownie batter)
Chill the cooled brownies before slicing to get neat, clean edges.