Heat the oven to 350°F (175°C) and coat a 9x13-inch pan with grease.
Combine the cake mix, softened margarine, and egg in a bowl, working until a dough forms. Then press that dough evenly into the bottom of the greased pan.
Pour the sweetened condensed milk over the dough layer, spreading it evenly. Then scatter the chopped pecans and brickle baking chips on top.
Bake for 25 to 30 minutes in the preheated oven, or until the edges turn golden brown.
Let the bars cool completely, then cut them into 12 servings.